Badr-El-Boudour Bidouche

Thierry Lubin
email: thierry.lubin@univ-lorraine.fr

Smaïl Mezani

Transient Performance of a Magnetically Geared Induction Machine

Keywords: Induction motor, magnetic gear, transient model, stability

Purpose -The purpose of this paper is to investigate the transient performance of an induction machine coupled with a magnetic gear for industrial applications with low speed and high torque requirements. This new solution increases mechanical reliability and does not require maintenance and lubrication. The main objective is to study the direct-on-line starting ability of the electrical machine and its stability regarding a sudden variation of the load torque.

Design/Methodology/Approach -A non-linear analytical model for the induction machine and the magnetic gear is first developed. The model is then linearized around an operating point to obtain the transfer function between the load angle and the electromagnetic torque from which an analytical expression for the mechanical resonant frequency is obtained.

Finding -It is shown that the direct on-line starting is possible if the moment of inertia of the load is not greater than a maximum value. Moreover, it is demonstrated that this new system present inherent overload protection.

Originality/Value -A new high-performance direct-on-line starting electrical machine is proposed to achieve high torque at low speed without mechanical gear to improve reliability and reduce maintenance.

Introduction

A new concept of a Magnetically Geared Induction Motor (MaGIM) was introduced by [START_REF] Mezani | Magnetically Geared Induction Machines[END_REF] in order to replace the conventional system that combines an induction motor IM to a mechanical gear for applications with low speed and high torque requirements. The main objective is to improve performance and reliability. A design procedure for a MaGIM rated at 1 kW -45 rpm and intended for a constant speed operation on the grid (400V/50Hz) has been developed in [START_REF] Bidouche | Design and analysis of a magnetically geared induction machine[END_REF]. Both electromagnetic and thermal analyses have been carried out using analytical computation tools. This design was carried out to optimize the steady state operation.

The present paper addresses transient analyses of MaGIM. Indeed, dynamic model is one of the key steps to validate the design process of an electrical actuator [START_REF] Adkins | The General Theory of Alternating Current Machines[END_REF]. Because the MaGIM integrates a magnetic gear whose torsional stiffness is much lower than mechanical gears, oscillations of speed and torque usually appear during transient variations of load. A passive reduction of the oscillations in magnetic gears can be obtained using damper windings as in synchronous generators. The authors in (Franck, 2011) showed the benefit of using dampers in reducing oscillations and settling time but additional losses due to space harmonics may be important. In magnetically geared PM machines [START_REF] Montague | Nonlinear Control of Magnetically-geared Drive-trains[END_REF], [START_REF] Bouheraoua | Slip recovery and prevention in pseudo direct drive permanent-magnet machines[END_REF], linear and non-linear control strategies are proposed to ensure better stability and rapid recovery from slipping during transient operation of magnetically-geared drive-trains.

The computation of the transient behavior of magnetically geared machines can be done by finite element analyses [START_REF] Ho | Transient analysis of a magnetic gear integrated brushless permanent magnet machine using circuit-field-motion coupled time-stepping finite element method[END_REF], Franck, 2011). Obviously, this leads to precise predictions of the electromechanical quantities taking into account magnetic saturation and circuit coupling. Nevertheless, FE methods solve time-dependent PDEs which requires long computation time not compatible with real time control requirements.

The preferred method for transient analyses of magnetic gears employs circuit models coupled to mechanical equations to predict the transient state by solving ODEs [START_REF] Desvaux | Analysis of the dynamic behaviour of magnetic gear with nonlinear modelling for large wind turbine[END_REF]. This technique is used in this paper in connection with the dq model of an induction motor to study the dynamic behavior of a MaGIM that operates on the grid. One question to be answered is: can this machine start on the grid without problem of stability for the magnetic gear?

Operating principle of the MaGIM

The MaGIM is shown in Fig. 1. It consists of a magnetic gear [START_REF] Rasmussen | Development of a high-performance magnetic gear[END_REF][START_REF] Hafla | Efficient design analysis of a novel magnetic gear on a high performance computer[END_REF][START_REF] Lubin | Analytical computation of the magnetic field distribution in a magnetic gear[END_REF]) coupled to a reverse type induction motor with p pole pairs. The magnetic gear represents the external part of the MaGIM while the IM represents the internal part (wound rotor machine). The high-speed (HS) rotor is the common part of the IM and the gear. The conventional magnetic gear involves two rotors and a fixed armature [START_REF] Atallah | A Novel High-Performance Magnetic Gear[END_REF][START_REF] Costa Neves | Analysis of a magnetic gear integrated Halbach generator[END_REF].

The MaGIM is supplied by the grid and can be used for low speed application requiring high starting torque. The electromagnetic torque from the IM moves the high-speed rotor. Then the magnetic field created in the air-gap by the pi polepairs permanent magnets (PM) of inner HS rotor is modulated by the Ps ferromagnetic pole pieces. The external armature being held stationary, the obtained field interacts with the magnetic field generated in the airgap by the po PM pole-pairs of this armature in order to transmit the torque to the low-speed (LS) rotor [START_REF] Liu | Design and analysis of interior magnet outer-rotor concentric magnetic gears[END_REF][START_REF] Filippini | An optimization tool for coaxial magnetic gear[END_REF]. The combination po=Ps-pi results in the highest torque transmission capability of the gear [START_REF] Atallah | A Novel High-Performance Magnetic Gear[END_REF]. The resulting gear ratio Gr is given by: 𝐺 𝑟 = 𝑃 𝑠 𝑝 𝑖

(1) To achieve the electromagnetic design of the MaGIM, analytical models for preliminary computations and finite-element simulations for more precise results were used [START_REF] Bidouche | Design and analysis of a magnetically geared induction machine[END_REF]. With the active dimensions obtained by the electromagnetic design, the gear exhibits a pull-out torque of 350 Nm. Table 1 gives the values of the main parameters of the MaGIM.

Transient Model of the MaGIM

A classical transient d-q model for the IM is used [START_REF] Adkins | The General Theory of Alternating Current Machines[END_REF]. This model is based on the theory of magnetically coupled electrical circuits. This model, linked to the stator (ωs = 0), is obtained by using Park's transformation. As shown in (2), this model is written by highlighting the measurable and easily accessed electrical parameters of the induction machine, such as the rotor time constant  𝑟 and the total leakage coefficient 𝜎. In (2), Ids, Iqs are the stator current in the d-q reference frame, and φdr and φqr are the rotor flux. The pulsation hs is the IM rotor speed (high-speed) and p is the number of pole-pairs of the IM. The electromagnetic torque can be defined as a function of these variables (3).

𝛤 𝑒𝑚 = 𝑝 𝑀 𝐿 𝑟 (𝜑 𝑑𝑟 . 𝐼 𝑞𝑠 -𝜑 𝑞𝑟 . 𝐼 𝑑𝑠 )

(3)

The main parameters for the IM and for the magnetic gear are given in Table 1 [START_REF] Bidouche | Design and analysis of a magnetically geared induction machine[END_REF]. The gear ratio being relatively high, the IM transmits a low torque value on the HS rotor. Hence, it was possible to achieve a MaGIM design [START_REF] Bidouche | Design and analysis of a magnetically geared induction machine[END_REF]) with a relative low value for the flux density in the teeth (around 1.3T) and the air-gap (around 0,6T) of the IM which works practically under linear condition in steady-state. Therefore, a linear d-q model as the one used in this paper with the parameters given in Table 1 is sufficient to predict the transient performance of the MaGIM. Moreover, the electromagnetic torque pulsations at 50Hz are largely filtered by the mechanical system as shown in Fig. 5. As a result, the

{ 𝑑𝐼 𝑑𝑠 𝑑𝑡 = - 1 𝜎𝐿 𝑠 [(𝑅 𝑠 + 𝑀 2 𝐿 𝑟  𝑟 ) 𝐼 𝑑𝑠 - 𝑀 𝐿 𝑟  𝑟 𝜑 𝑑𝑟 - 𝑀 𝐿 𝑟 𝑝 ℎ𝑠 𝜑 𝑞𝑟 + 𝑉 𝑑𝑠 ] 𝑑𝐼 𝑞𝑠 𝑑𝑡 = - 1 𝜎𝐿 𝑠 [(𝑅 𝑠 + 𝑀 2 𝐿 𝑟  𝑟 ) 𝐼 𝑞𝑠 - 𝑀 𝐿 𝑟 𝑝 ℎ𝑠 𝜑 𝑑𝑟 - 𝑀 𝐿 𝑟  𝑟 𝜑 𝑞𝑟 + 𝑉 𝑞𝑠 ] 𝑑𝜑 𝑑𝑟 𝑑𝑡 = 𝑀  𝑟 𝐼 𝑑𝑠 + 1  𝑟 𝜑 𝑑𝑟 -𝑝 ℎ𝑠 𝜑 𝑞𝑟 𝑑𝜑 𝑞𝑟 𝑑𝑡 = 𝑀  𝑟 𝐼 𝑑𝑠 -𝑝 ℎ𝑠 𝜑 𝑑𝑟 + 1  𝑟 𝜑 𝑞𝑟 (2)
maximum value reached by the electromagnetic torque during the starting will have a little impact on the stability, even though magnetic saturation is taken into account in the modeling.

To take into account the magnetic saturation on the transient performances, a saturation factor could be added in the d-q model [START_REF] Brown | A method of including the effects of main flux path saturation in the generalized equations of a.c. machines[END_REF]. This saturation factor can be obtained by the no load test or computed by finite element simulations. As known, this saturation factor depends on the electrical currents in the machine (stator and rotor) and has an impact on the stator and rotor flux-linkages (so on the electromagnetic torque as well) during the transient.

The block diagram of the MaGIM is given in Fig. 2 where Jh and Jl are the moment of inertia of the HS and LS rotors respectively, Fh and Fl are the friction coefficients, and em, h, l, and ch represent the electromagnetic, the HS , the LS, and the load torque, respectively.

Fig. 2. Block diagram of the MaGIM

The mechanical model of the magnetic gear is obtained from the second Newton's law. As shown in Fig. 3, we consider a sinusoidal variation with respect to the load angle  for h and l [START_REF] Atallah | A Novel High-Performance Magnetic Gear[END_REF][START_REF] Mezani | Magnetically Geared Induction Machines[END_REF]. For a magnetic gear, the torque ripples depend on the pole-pairs combination between the two rotors. It is shown in [START_REF] Atallah | A Novel High-Performance Magnetic Gear[END_REF][START_REF] Zhu | Influence of Design Parameters on Cogging Torque in Permanent Magnet Machines[END_REF] that the torque ripples decrease with the cogging torque factor Cf which depends on po and Ps. For the studied magnetic gear, we have po = 29 and Ps = 31, which results in the minimal value of Cf = 1. Therefore, the torque is practically ripple-free so we can assume a sinusoidal variation of h and l with the load angle .

The dynamic equations are written for each rotor as reported in (4). The load angle  is defined in (5).

Linearized magneto-mechanical model of the magnetic gear

Considering a sinusoidal variation for the transmitted torque as shown in Fig. 3, the HS and LS torque h and l, depend on the magnetic gear properties such as the maximal torque Γmax, the load angle 𝛷 defined in (5) and the gear ratio Gr.

with hs = dh/dt and ls=dl/dt.

As shown in (4), the mechanical transient model of the MaGIM is non-linear due to the sinusoidal term. In order to obtain a linear model, a first order Taylor expansion of the sine function is considered around an operating point corresponding to 𝛷 = 𝛷 0 . This gives us the natural frequency expression of the shaft line shown in Fig. 2. As shown in Fig. 3, the operating point is defined for a load torque value Γl0 that corresponds to 𝛷0, where 𝛷 0 < 𝜋 2 and 𝛤 𝑙0 < 𝛤 𝑚𝑎𝑥 .

The use of Laplace transform allows writing the linear equations of the magnetic gear in matrix form (6). This system of equations reveals an important parameter called the torsional stiffness coefficient K (Nm/rad) given by ( 7). The torsional stiffness K depends on the parameters Γmax and Ps of the magnetic gear. Its value for the studied magnetic gear is around 10 kNm/rad, which is 50 times smaller than the torsional stiffness coefficient of a classical mechanical gear whose typical value is greater than 50 kNm/rad. This low value for the torsional stiffness will be the source of large oscillations in the speed response during the transient, as shown later in the paper. To study the impact of the IM electromagnetic torque em on the load angle of the magnetic gear, we obtain from ( 5) and ( 6) the transfer function of the MaGIM:

𝐹 𝑡 (𝑠) = 𝜙(𝑠) 𝛤 𝑒𝑚 (𝑠) = 𝐴 1 + 𝜏 1 𝑠 (1 + 𝜏 2 𝑠)(1 + 2𝑚 𝜔 0 𝑠 + 1 𝜔 0 2 𝑠 2 ) (8)
This corresponds to a third-order transfer function. From ( 6), ( 7) and ( 8), it is possible to identify the parameters of the transfer function: the steady state gain A, the time constants 1 and 2, the undamped resonant frequency 𝜔 0 and the damping factor m. It is important to note that the parameters of the transfer function (8) depend on the operating point characterized by 0. These parameters are expressed in the following equations

Fig. 4 shows the Bode diagram corresponding to the third-order transfer function ( 8) with the parameters given in Table 1 and Table 2 and by considering 𝛷0 = 0 (no-load condition). The Bode's diagram gives us a simplified graphical representation of ( 8)

in order to study the MaGIM behavior in the frequency domain.

We can observe in Fig. 4 that the gain amplitude goes to a maximum value of around -5dB for a resonant frequency of 47 rad/s. The gain amplification at this frequency highlights the classical resonance phenomenon. This phenomenon is amplified by the low value of the damping coefficient (11) which is equal to m = 0.043 for the studied line shaft. It is important to note that if an electromagnetic torque of the IM is characterized by a pulsation close to this resonant frequency, the disturbances will be amplified and the risk of overload becomes significant. We can define a similar Bode diagram with respect to the load torque (with the same resonant frequency) with the same conclusion.

Results and discussions

In order to validate the established analytical models, simulation studies that uses the non-linear models of the induction machine and the magnetic gear (2)-( 5) are conducted (MaGIM parameters are given in Tables 1 and2).

In this section, the dynamic behavior of the MaGIM is first evaluated for a direct on-line start at rated voltage and frequency (400V; 50Hz) and under no-load condition. The main objective is to verify if the MaGIM can start without dropping out. Then we study the speed responses to a load torque step of 100 Nm and for overload condition. In order to show the impact of the resonant frequency on the load angle, a load torque combining an average value and a sinusoidal disturbance with different frequency values will be applied to the MaGIM. The main objective is to show the impact of the resonant frequency on the load angle. Finally, we will show the influence of the load inertia Jl on the transient responses.

Direct on-line start

A direct on-line start under no-load condition is firstly studied. The mechanical parameters of the MaGIM are given in table 2. It is important to note that Jl includes the load inertia. Fig. 5 shows the speed variations for the LS and HS rotors during the start-up. Fig. 6 shows the torque on the LS and HS rotors, and the electromagnetic torque of the induction machine. Fig. 7 gives the load angle variation during the starting. First of all, we can observe in Fig. 5 to Fig . 7 that the direct starting on the grid is possible. The HS rotor reaches a speed of around 750 rpm with a response time of less than 1s, whereas the LS rotor speed is around 50 rpm in steady-state, which is in the gear ratio defined in (1). The maximum LS rotor torque reaches a value of 85 Nm which doesn't exceed the pull-out torque of the magnetic gear (max = 350 Nm). We can observe significant oscillations during the transient phase. They are characterized by a pseudo-period of 140 ms and a very low damping coefficient. This is a classical behavior for magnetic gear that exhibits a low value for the torsional stiffness compared to a mechanical gear [START_REF] Desvaux | Analysis of the dynamic behaviour of magnetic gear with nonlinear modelling for large wind turbine[END_REF]. These large oscillations only exist during the transient (starting, sudden load torque…) and cause vibrations that can be the source of mechanical fragility and noise.

Moreover, it can be problematic to achieve high performance for speed or position control in servomechanism applications. Fig. 7 shows that the load angle reaches a maximum value equal to 17° during the starting, which remains much lower than 90° corresponding to the stability limit for the magnetic gear.

Response to a sudden load torque

Once the machine has started, we applied a load torque step of 100 Nm on the LS rotor at t = 5s. Fig. 8 to Fig. 10 show the transient responses for the low speed torque, the rotational speed of the HS and LS rotors, and for the load angle.

We can observe in Fig. 8 that this load torque step generates large oscillations on the LS torque l with a maximum value of around 190 Nm. However, this maximum value remains lower than max and the operation remains stable after the transient.

These oscillations are characterized by a pseudo-period of about 137 ms, slightly lower than the 140 ms obtained under no-load condition. With the parameters listed in Tables 1 and2 and from equations ( 10) and ( 11), we calculate a pseudo-period of 132 ms. Note that this value is close to the one obtained by the analytical approach based on the linearized model which uses Taylor's first order approximation.

As it can be seen in fig. 10, we can observe the same oscillation for the load angle during the transient. The value of the load angle 𝛷 does not exceed 40°. Regarding the rotational speed of the LS and HS rotors shown in Fig. 9, we obviously note that their values decrease when the torque step is applied. Also, we can observe low speed ripples during the transient phase. This is due to the large value of the inertia. Fig. 11 and Fig. 12 show that the stability is maintained for a step load torque of 210 Nm that corresponds to the rated torque of the MaGIM. We can observe in Fig. 12 that the load angle reaches a value of around 100° during the transient without the loss of stability. It is important to make the difference between the dynamic stability and the static stability. As for a synchronous machine, it is well known that the load angle may exceed the value of 90° during the transient, as shown in Fig. 12, without the loss of stability at steady state. The stability can be predicted by the method of area equality but this is out of the scope of this paper. It greatly depends on the pull-out torque value of the magnetic gear (max = 350 Nm) compared to the nominal torque of the MaGIM. Here the magnetic gear has been designed to keep a margin of more than 100 Nm in order to ensure the stability under transient and steady-state conditions.

Overload condition

It is well known that magnetic gears offer substantial advantages compared to mechanical gears such as reduced maintenance, improved reliability, minimum acoustic noise and inherent overload protection [START_REF] Atallah | A Novel High-Performance Magnetic Gear[END_REF][START_REF] Rasmussen | Development of a high-performance magnetic gear[END_REF][START_REF] Hafla | Efficient design analysis of a novel magnetic gear on a high performance computer[END_REF][START_REF] Lubin | Analytical computation of the magnetic field distribution in a magnetic gear[END_REF]. In this sub-subsection, we present some results related to the self-overload protection inherent to magnetic gears.

To highlight this phenomenon, we apply (t =5s) a load torque of 400 Nm which is higher than max. Figs. 13 to 15 show the speed variation of the HS and LS rotors, and the low speed torque, respectively.

As can be seen in Fig. 14, this operation causes the stall of the low speed rotor. That results in significant oscillations on the output torque (between -350 and +350 Nm). As shown in Fig. 13, the HS rotor continues to rotate at a speed of 750 rpm because the induction machine is connected to the grid. This operation is harmful for the MaGIM due to the vibratory movement of the low speed rotor which can cause mechanical wear. In an extreme case characterized by prolonged operation in this state, the deterioration of the device may be irreversible. It is therefore important to stop the power supply rapidly.

Sinusoidal disturbance on the load torque

In order to show the impact of the resonant frequency on the MaGIM behavior, we apply a load torque characterized by an average value 0 = 100 Nm and a sinusoidal variation. This sinusoidal variation is defined by a small amplitude  = 10 Nm and a frequency ω (12). Fig. 16 shows the load torque variations with ω = 4rd/s. 𝛤 𝑐ℎ = 𝛤 0 + 𝛥𝛤. 𝑠𝑖𝑛(𝜔𝑡) (12) In order to study the impact of the frequency ω on the performance of the MaGIM, simulations are done for three values of ω by using the non-linear model: ω < ω0, ω = ω0 and ω > ω0 where ω0 is given by (10). For a mean load torque of 100 Nm (𝛷 0 = 18°), the resonant frequency is equal to ω0 = 47 rd/s. Fig. 17 to Fig. 19 show the load angle variation for ω = 4 rd/s, ω = ω0 =47 rd/s and ω = 100 rd/s respectively. When ω < ω0, it can be seen in Fig . 17 that the variation in the load angle remains small because of the frequency value being far from the resonant frequency. We observe the same behavior in Fig . 18 which is obtained for ω > ω0 but with a more prononciate attenuation for the load angle, as it can be predicted by the Bode diagram of Fig. 4.

If the frequency value is equal to the resonant frequency (ω = ω0), the system is severely disrupted, as shown in Fig. 19 where the variation on the load angle is very important and generates large oscillation on the rotor speed which can lead to mechanical problems.

It is worth noting that all these behaviors can be predicted by using the Bode diagram given in Fig. 4 and by the analytical expression of the resonant frequency given in (10).

Impact of the low speed inertia Jl on the transient response

As mentioned previously, it is necessary to avoid any operation around the resonant frequency otherwise the risk of instability of the system increases that could lead to a stalling scenario. Since the expression of the resonant frequency ω0 (10) depends on the values of the parameters K, Jl, Gr and Jh, and since only the inertia of the LS rotor can vary with the load (K, Gr and Jh depend on fixed geometric parameters), we study in this part the impact of the LS inertia Jl on the system behavior during the transient. Fig. 20 shows the speed of the HS and LS rotors for a direct-on-line starting with a LS rotor inertia fixed to Jl = 50 kg.m² (around 10 times the one corresponding to Fig. 5). We notice significant oscillations and a relatively long time response in comparison to Fig. 5 but starting is still possible. The load angle shown in Fig. 21, presents large oscillation during the transient phase with a maximum value of about 120°. This peak value is higher than 90°. However, there is no uncoupling between the HS and the LS rotors. This is due to the well-known dynamic stability criteria, which is equivalent to that of a synchronous machine connected to the grid (equal area criterion). This value for the LS rotor moment of inertia Jl is designated as a critical value since, as shown in Fig. 22 and Fig. 23, beyond a value of 50 kg.m² the machine stalls for Jl = 53 kg.m 2 . It is clear from Fig. 22 that the LS rotor does not start whiles the HS rotor is rotating, therefore the load angle tends toward infinity as show in Fig . 23.

Conclusion

This paper presents the transient performances for a new type of electrical machine, the MaGIM. The MaGIM consists of an IM machine coupled to a magnetic gear. This new electrical machine can be used for applications directly connected to the grid that requires low speed and high torque. Dynamic simulations for a direct-on-line starting for no load and for a sudden variation of load torque were presented. The overload self-protection of the machine was shown as a result of a load torque higher than the maximum torque. We have given a simple expression for the resonant frequency of the MaGIM and we have shown its validity in different cases. Finally, we studied the impact of the mechanical parameters on the transient behavior, especially the one which involves the moment of inertia of the LS rotor. Its shown that there is a maximum limit that must not be exceeded otherwise the MaGIM will not start.

Fig. 1 .

 1 Fig. 1. 2D view of the MaGIM with pi = 2, Ps = 31 and po = 29.

Fig. 3 .

 3 Fig. 3. Low speed torque as a function of the load angle

Fig. 4 .

 4 Fig. 4. Bode diagram of the transfer function Ft(s)

Fig. 5 .

 5 Fig. 5. Rotationnal speed for the LS and HS rotors during the start-up.

Fig. 8 .

 8 Fig.8. Low speed torque l for a step load torque of 100Nm at t = 5s.

Fig. 10 .

 10 Fig.10. Load angle variation during during a step load torque of 100Nm at t = 5s.

Fig. 11 .

 11 Fig.11. Low speed torque l for a step load torque of 210 Nm (rated torque) at t = 5s.

Fig. 12 .

 12 Fig.12. Load angle variation during a step load torque of 210 Nm at t = 5s

Fig. 13 .

 13 Fig. 13. HS rotor speed in overload condition.

Fig. 14 .

 14 Fig. 14. LS rotor speed in overload condition.

Fig. 15 .

 15 Fig. 15. Low speed torque in overload condition.

Fig. 16 .

 16 Fig. 16. Sinusoidal load torque variation with ω = 4 rad/s.

Fig. 17 .

 17 Fig. 17. Load angle variation for ω = 4 rad/s.

Fig. 18 .

 18 Fig. 18. Load angle variation for ω = 100 rad/s.

Fig. 19 .

 19 Fig.19. Load angle for sinusoidal torque of ω = ω0 = 47rad/s.

Fig. 20 .

 20 Fig.20. Rotational speed of the HS and the LS for Jl = 50 kg.m 2 .

TABLE 1 . PARAMETERS OF THE MAGIM Magnetic gear parameter Value Inner

 1

	rotor pole-pairs pi	2
	Stationary armature poles-pairs po	29
	Number of ferromagnetic pole-pieces Ps	31
	Gear ratio Gr	15.5
	Pull-out torque 𝚪max	350 Nm
	IM electrical parameter	Value
	Stator inductance Ls	0.3 H
	Rotor inductance Lr	0.08 H
	Mutual inductance M	0.15 H
	Stator resistance Rs	6.6 Ω
	Rotor resistance Rr	2.2 Ω
	Rotor time constant r	36 ms
	Total leakage coefficient σ	0.062
	Number of pole-pairs p	4

  𝜙 = 𝑝 𝑖 . 𝜃 ℎ -𝑃 𝑠 . 𝜃 𝑙

		𝑑𝛺 ℎ𝑠 𝑑𝑡	=	1 𝐽 ℎ	𝛤 𝑒𝑚 -	𝐹 ℎ 𝐽 ℎ	. 𝛺 ℎ𝑠 -	𝛤 𝑚𝑎𝑥 𝐽 ℎ . 𝐺 𝑟	. 𝑠𝑖𝑛(𝜙)
	{	𝑑𝛺 𝑙𝑠 𝑑𝑡	=	𝛤 𝑚𝑎𝑥 𝐽 𝑙	. 𝑠𝑖𝑛(𝜙) -	𝐹 𝑙 𝐽 𝑙	. 𝛺 𝑙𝑠 -	𝐽 𝑙 𝛤 𝑐ℎ	(4)

TABLE 2

 2

	MECHANICAL PARAMETERS OF THE MAGIM
	Mechanical parameter	Value
	HS rotor inertia Jh	0.2 kg.m²
	LS rotor and load inertia Jl	4.6 kg.m²
	Friction coefficient for the HS rotor Fh	7e-3 Nm/rad/s
	Friction coefficient for the LS rotor Fl	1.7 Nm/rad/s


Hassane Oudadesse
email: hassane.oudadesse@univ-rennes1.fr

Sanaa Najem

Siwar Mosbahi

Nicolas Rocton

Jihen Refifi

Hafedh El Feki

Bertrand Lefeuvre

Aq1hassane Oudadesse

| Siwar Mosbahi

Jihen Refi Fi

| Bertrand Lefeuvre

Development of

Keywords: chemical reactivity, chitosan, hybrid biomaterial, nano bioactive glass, porosity, scaffold

1INTRODUCTION

The tissue engineering domain is a promising research field for bone biomaterials development. Natural implants and synthetic biomaterials are used to repair human body parts and to restore their biological functions. An ideal implant for the regeneration of damaged tissues is a synthetic porous material. In our research group, we focused on porous glass ceramics and. The scaffold is a material that presents a homogeneous and organized porosity in its three-dimensional (3D) architecture and in the form of stratified layers.

These scaffolds combined with organic molecules, bisphosphonates such as clodronate, risedronate, raloxifene, and/or biopolymers are able to play double functions: regeneration of bone tissue and contribution of certain bone pathologies by drug delivery. Then they contribute to being resorbed after a certain period of their insertion in bone sites [START_REF] Balanta | Utilización de quitosanoprocedentedelmicelio de Aspergillus Níger y su aplicación en regeneración de tejidos[END_REF][START_REF] Verified | Review of bioactive glass: From Hench to hybrids[END_REF][START_REF] Verified Mozafari | Synthesis, characterization and biocompatibility evaluation of sol-gel derived bioactive glass scaffolds prepared by freeze casting method[END_REF]. For the development of an optimal scaffold, we adopted the necessity of stable direct contact between bone and the scaffold surface as a critical requirement. Excellent biocompatibility, a controllable biodegradability, and an adapted mechanical strength were used capital properties for an ideal scaffold used for several applications in tissue engineering.

Several biodegradable polymers such as poly(caprolactone), poly(vinyl alcohol), and natural polymers such as collagen and biopolymers like chitosan [START_REF] Verified Hirano | Chitosan as an ingredient for domestic animal feeds[END_REF] are used in the biomaterials field. They demonstrated their positive effect on bone restoration. Chitosan is a natural biopolymer extracted from the chitin by a partial chemical or enzymatic deacetylation. Our previous works demonstrated its effect on the osteoporosis phenomenon when it is associated with bioactive glass biomaterials. Chitosan represents an ideal material for uses in tissue engineering because of its several biological characteristics such as its good biocompatibility, biodegradability, bioinert, and its capacity to adsorb such protein ( Usually, by comparison to the microphase ceramics, the interaction between cell and material was well reported on the surface of nanophase ceramics [START_REF] Verified | Enhanced functions of osteoblasts on nanophase ceramics[END_REF]. Using nano bioactive glass aimed to enhance the mechanical and biological performance of scaffolds. Improvement of bone cells such as osteoblasts and their effect on the scaffold substrate encourage their use as bone biomaterials (Alves, Leonor, Azevedo, Reis, & Mano, 2010). Thus, several studies aimed to develop specific methods for the synthesis of porous scaffold. [START_REF] Verified Whang | A novel method to fabricate bioabsorbable scaffolds[END_REF]. The well-employed method is the thermally induced phase separation (TIPS) [START_REF] Verified Ma | A preliminary in vitro study on the fabrication and tissue engineering applications of a novel chitosan bilayer material as a scaffold of human neofetal dermal fibroblasts[END_REF]Nam & Park,1999;[START_REF] Verified Whang | A novel method to fabricate bioabsorbable scaffolds[END_REF]. This method is based on the decrease of solution temperature in order to generate the homogeneous biodegradable polymer solution phase separation. It can induce polymer-poor phase and polymer-rich liquid phase [START_REF] Verified Han | Biodegradable membranes for the controlled release of progesterone. 1. Characterization of membrane morphologies coagulated from PLGA/progesterone/DMF solutions[END_REF]. The growing and coalescence of the polymer-poor phase allow the introduction of multiple pores in scaffolds. When the temperature was well attenuated and lead to the solution freezes, we obtained the separation phase between solid and liquid that formed frozen solvent and polymer-rich phases. Finally, the frozen solvent removal leaves place for pores.

Our study believed that the freeze-gelation process is very important in terms of either energy and time, very easy to employ, and produces less residual solvent. For that, it was well used in the development of scaffold material. This new technique was well evaluated through the regulation of several parameters such as the freezing temperature, and both acetic acid and ethanol concentrations in the gelation environment. Scaffold architecture is very essential for tissue engineering development. In the freeze-gelation technique, several parameters can influence the scaffold structure. Over the freezing technique, the temperature decrease leads to the formation of the phase separation permitting the apparition of ice and chitosan-rich phases. At the phase separation step, the scaffold porosity, architecture, and characteristics are defined. Thus, the freezing temperature of the BGN/CH solution is an essential variable parameter. At the gelation step, chitosan phases undergo condensation phenomena and the ice left its place for the creation of pores after the lyophilization process.

In the present work, the chitosan solution was prepared after its dissolving in the acetic acid solvent, which constitutes another variable parameter. In this study, the development of the sol-gel technique has been adapted for the elaboration of bioactive glass nanoparticles. The chitosan/bioactive glass nanoparticles (BGNs) as a hybrid scaffold was prepared by the freeze-gelation method based on the TIPS. This composite scaffold was characterized, and its bioactivity and biodegradability have been studied relevant to biomedical applications.

2EXPERIMENTAL PROCEDURE

2.1Synthesis of BGN and the BGN/CH (20:80) hybrid scaffolds

The sol-gel process was used for the synthesis of the BGN (SiO 2 :CaO:P 2 O 5 [mol] = 55:40:5). Calcium nitrate solution and tetraethylorthosilicate (TEOS) were blended and then followed by the addition of the citric acid in the goal to fix the pH value to 1-2. Under, vigorous agitation, the obtained solution was slowly supplemented to the solution of ammonium dibasic phosphate. Over the dropping step, the pH of the solution was adjusted to a value of around 10-11, employing the NH 3 solution.

After 48 hr of agitation and 24 hr of maturation, the solution was centrifuged leading to the separation between the precipitate and initial product in a 200 ml of 2% PEG-water solution. The obtained powder was lyophilized for 48 hr and followed by its calcination at 600°C for 3 hr. Finally, we obtained our BGN powder. This work detailed the hybrid porous scaffolds BGN/CH employing newly developed freezegelation process. The freeze-gelation is based on the principle of thermally induced phase separation (Figure 1). Two percent of polymer solution was obtained by the dissolving chitosan in an acetic acid aqueous solution (1 M). Nano bioactive glass particles (0.4%) were suspended in the deionized water for 1 hr under ultrasonication.

FIGURE 1Schematic representation of bioactive glass nanoparticle (BGN)/chitosan (CH) composite scaffold fabrication method (freeze-gelation)

The suspension was added to the previously prepared chitosan solution. Then, the chitosan/BGN suspension was put at -20°C, in a Petri dish, during 24 hr (Bi et al., 2011).

The frozen sample was soaked in a solution of NaOH/ethanol in the goal to adapt its pH value in order to permit the chitosan gelation. The NaOH/ethanol solution was cooled to -20°C in order to favor the chitosan gelation process below the chitosan freeze point. Indeed, the NaOH aqueous solution leads to the alkalinity for gelation and the ethanol leads to decrease in the freezing point. Prepared porous composite scaffold (BGN/CH) through freeze-gelation and after freeze-drying processes is presented in Figure 2.

FIGURE 2Image of the porous bioactive glass nanoparticle (BGN)/chitosan (CH) composite scaffold prepared by the freeze-gelation method after freeze-drying

The success of elaborated scaffolds for use as filling biomaterials depends on the porous structure and architecture. The freeze-gelation technique contained several processes, which influence scaffolds structure. In the present work, we used the acetic acid as a solvent for the preparation of chitosan solution. The acetic acid concentration ranged from 0.2 to 2 M and the effect of this variation on the scaffold structure was well detailed.

2.2Morphological evaluation of hybrid scaffolds

The morphological structure of the obtained material (BGN/CH) has been evaluated by scanning electron microscopy (SEM). Before the start of the morphological analysis, samples have been metalized using a layer of gold-palladium.

2.3Functional groups evaluation: Fourier-transform infrared spectroscopy

The Bruker Equinox 55 spectrometer was used for the infrared spectroscopy study. Ten milligrams of dried composite scaffolds were ground and homogenized with KBr powder and pressed in the order to form a suitable pellet for the infrared analysis. Data were collected between 4,000 and 400 cm -1 and lead to collect the functional groups composed of the hybrid scaffolds.

2.4Structural analysis and surface areas

The powders of the obtained scaffolds were analyzed by X-ray diffraction (XRD) in order to have more information on their structure. XRD diagrams were recorded by using a Panalytical diffractometer (Cu Kα radiation, 40 kV, 30 mA) in the 2θ range of 5°-90° with a step size of 0.026° and counting time of 30 s for each step.

The specific surface area was measured using the Brunauer-Emmett-Teller (BET) N2 adsorption-desorption process (Flowsorb II 2300, Coultronics France SA). The pore volume was also determined.

2.5Chemical reactivity evaluation

The chemical reactivity of the obtained BGN/CH scaffolds was evaluated by soaking of 30 mg of powder in 20 ml of the simulated body fluid (SBF) having the same composition of the blood plasma. Samples were immersed during 1, 3, 5, and 7 days under 37°C and 50 rpm/min to allow the similar conditions of the physiological environment.

SBF composition as presented in our previous works and as described by [START_REF] Verified Kokubo | How useful is SBF in predicting in vivo bone bioactivity[END_REF]) is shown in Table 1. After each immersion period, the powder was rinsed with water, and then with alcohol in order to stop the chemical reaction, while the solution was stored in the fridge under 4°C in order to evaluate the chemical exchange between biomaterial and SBF solution.

After its lyophilization, the powder was characterized by several physicochemical techniques such as infrared spectroscopy, XRD, and SEM to allow and understand the chemical reactivity of the immersed biomaterial.

2.6In vitro biodegradation

The in vitro behavior of hybrid BGN/CH was evaluated in phosphate-buffered saline (PBS) under 37°C. Materials with dimensions of 10 × 10 × 2 mm -3 were soaked in 10 ml of PBS and were placed with a weak agitation in physiological condition (37°C) for 7 days. PBS chemical composition is detailed in Table 2. PBS solution was formed by the dissociation of NaCl and KCl, Na 2 HPO 4 and KH 2 PO 4 in an aqueous solution (distilled water) having a pH value of 7.4. The initial weight of scaffolds is called W i . Following all immersion delays, the material was rinsed with deionized water in order to eliminate all adsorbed ions on the surface and then dried. The dry weight is called W t. The liberation of scaffold elements in the BPS solution was measured by the following equation:

3RESULTS AND DISCUSSION

3.1Characterizations of the BGN/hybrid scaffold SEM of the obtained composite (Figure 3) showed that BGN/CH hybrid scaffolds present well-interconnected pores. The size of the obtained scaffolds pores varied from 100 to 300 μm as shown by the SEM analysis. The pore size of the scaffold varied between 100 and 300 μm. As presented in Figure 3, the BGNs are arranged on the walls of the scaffold with homogeneous dispersion. Good adhesion between the BGNs and chitosan biopolymer has been obtained and presented in Figure 3b (white arrows), noting that the cell size is about 10-100 μm. The pore size of the hybrid scaffolds is adapted to cell integration in the interior of the BGN/CH. Pores have a key role in the integration and differentiation of stem cells and also in the process of vascularization. The functions of pores depend on their size. In fact, large pores enhance the osteogenesis, the vascularization, and the oxygenation process. However, the smaller pores assign the osteochondral ossification. Also, the geometry of pores varied the type of growth factor present in the biomaterial (Karageorgiou & Kaplan, 2005). There are two benefits if using freeze-drying to remove the solvent: the first is to keep the temperature low enough that the polymer-rich region would not dissolve again and the second is to possess enough mechanical strength through the ice to prevent pore collapse during drying [START_REF] Verified | Preparation of porous scaffolds by using freeze-extraction and freeze-gelation methods[END_REF].

The XRD diagrams and thermal curve underline the amorphous structure of BGN (Figures 4 and5). In fact, nano bioactive glass illustrates the presence of only a diffraction halo observed between 15° and 40° (2θ) (Madhumathi et al., 2009) (Figure 4). The vitreous temperature of nano bioactive glass is 660°C (Figure 5). XRD of chitosan scaffold presents a peak at 21°. The diagram of the hybrid BGN/CH underlined the appearance of a new peak at 21° (2θ) this peak was replaced by a diffraction halo in the XRD pattern of BGN/CH hybrid scaffold. The disappearance of the chitosan peak in the XRD pattern of the composite confirmed its amorphous state and demonstrated the interaction between the BGNs and chitosan. FTIR spectra of the BGN/CH hybrid scaffold (Figure 6c) showed the presence of bands at 1,649 and 1,420 cm -1 . These bands underlined the first amine group and the secondary amine groups of chitosan, respectively. As compared to the chitosan, the hybrid scaffold (BGN/CH) showed the presence of two bands of P-O observed at 602 and 564 cm -1 and a band of Si─O─Si observed at 467cm -1 . In comparison to the FTIR spectra of BGN, the composite presents two peaks, which correspond to amine groups and modification in Si─O─Si band.

The presence of amine groups and the modification in the silicate band can be attributed to the interactions between the BGN and the chitosan. The broadband in the FTIR spectra of BGN (Figure 6a), from 3,100 to 3,470 cm -1 , corresponding to the O─H stretching absorption band was modified in the spectra of BGN/CH. The aliphatic C─H stretching band in the FTIR spectra of chitosan (Figure 6b) observed between 2,885 and 2,990 cm -1 disappears from the spectra of BGN/CH. The modification of peaks in the hybrid scaffold spectra confirmed that a chemical bond has taken place between the components. The bonding between chitosan and bioactive glass was assisted by the existence of silanol groups (Si─OH) in bioactive glass structure and surface as shown in Figure 7. Different amounts of BGN (20, 40, 60, and 80%) have been employed to synthesize BGB/CH by freeze-gelation method. The surface area and the porosity volume have been measured for the different composites by the BET method. The obtained results showed that for the hybrid scaffold BGN/CH with 20% of BGN the surface area is of about 26.63 m 2 /g. The surface area of the hybrid scaffold decreases to 13.81 m 2 /g with increasing of BGN amount to 80%. The same variations have been observed concerning the porosity volume. The porosity volume decreases from 7.60 to 6.10 mm 3 /g with increasing of BGN amount to 80%. These results were related to the results obtained in the literature, which show the increase of the surface area of the composite with the increasing chitosan amount. The obtained results are summarized in Table 3. To study the effect of the changes in acetic acid concentration on the structural properties of the BGN/CH hybrid scaffold, two acid concentrations were used: 2 and 0.5 M. The SEM micrograph of BGN/CH prepared by 2 M acetic acid concentration showed destruction in porous structure and the scaffold was not entirely porous as shown in Figure 8. During the gelation step of hybrid scaffold preparation, the acetic acid is neutralized by the NaOH solution; this neutralization reaction is the exothermic reaction. The heat release induced the melting of the scaffold and the collapse of the porous morphology of BGN/CH. The amount of heat release increases with increase of acetic acid concentration. Therefore, when we used a lower concentration of acetic acid during the freeze-gelation method, the amount of heat release was low and we obtained a BGN/CH hybrid scaffold with a good organization of porous structure as shown in Figure 8b. Indeed, the obtained porous structure of the scaffolds is very important for medical applications [START_REF] Verified Chesnutt | Design and characterization of a novel chitosan/nanocrystalline calcium phosphate composite scaffold for bone regeneration[END_REF][START_REF] Verified | Preparation and properties of nano-hydroxyapatite/chitosan/carboxymethyl cellulose composite scaffold[END_REF][START_REF] Verified Slivka | Porous, resorbable, fiber-reinforced scaffolds tailored for articular cartilage repair[END_REF]. In fact, the architecture of the pore enhances the integration and the differentiation of stem cells, mesenchymal cells, osteoblasts, and then the vascularization. The bioactivity of the BGN/CH has been tested. Scaffolds have been soaked in SBF solution at different periods from 1 to 7 days. The XRD studies of the hybrid scaffold (Figure 9) after 1 day of immersion showed two peaks at 31° and 45° (2θ) corresponding to hydroxyapatite (Madhumathi et al., 2009); the intensities of these peaks increase with the immersion time, during our study period of 7 days. To analyze the evolution of mineral deposits with immersion time in SBF, the ratio of peak intensities was calculated. Figure 10 showed the evolution of the ratio of intensities depending on the time immersion of the hybrid scaffold in SBF. This ratio increased from 1.48 after 1 day of immersion to 2.13 after 7 days of immersion. The deposition of minerals on the surface of biomaterials amounted to the rise of soaking times in the SBF solution. The BGN/CH bioactivity was justified by the presence of the hydroxyapatite layer at its surface after 7 days of incubation as shown in Figure 11a,b. The presence of this apatite layer on the surface of hybrid scaffolds underlines their chemical reactivity and ability to form a biological link with the surrounding environment. These data highlight the good use of this material for biomedical application. Figure 12a,b shows the in vitro degradation of the BGN/CH hybrid scaffold after 7 days of soaking in the BPS. From 1 to 7 days of soaking, the degradation rate of BGN/CH increases from 2.5 to 9%. Figure 12b showed the degradation rate of the pure chitosan scaffold for different times of incubation in PBS. The degradation rate increases from 15.3% after 1 day of immersion to 28.5% after 7 days of soaking. BGN/CH hybrid scaffold showed a significant decline in the degradation rate compared to the pure chitosan scaffold. Indeed, the porosity of these hybrid scaffolds enhances the penetration of the PBS solution within the porous structure of chitosan and makes degradation easier. The rate of resorption and degradation of biomaterials is an essential property for the bone graft evaluation. The dissociation of the ß-1,4-N-acetyl glucosamine groups of chitosan chains is provided by lysozyme. The dissociation of the ß-1,4-N-acetyl glucosamine groups of chitosan chains is provided by lysozyme. This process results from the liberation of amino sugars. The association of BGN and chitosan leads to the attenuation of the degradation rate, which was explained by the neutralization of the dissociation of the chitosan acidic product, by the alkali groups of the BGN (Silver, Deas, & Erecińska, 2001).

4CONCLUSIONS

BGN/CH hybrid scaffolds were synthesized using the freeze-gelation method for potential applications as bone graft materials for tissue regeneration. The obtained hybrid scaffolds are macroporous biomaterials with pore size ranged between 150 and 300 μm and sufficient microporosity for cell infiltration. The BGN/CH with 20% of the BGN amount presents a better surface area. Seven days after soaking in the PBS solution, these biodegradable scaffolds lost 9% of their weight. As compared with pure chitosan, the addition of BGN retarded the level of chitosan degradation. The chemical reactivity of the obtained hybrid scaffolds was showed through the deposition of a hydroxyapatite layer at the material surface after its incubation in the SBF solution. In conclusion, the bioactivity of bioactive nanoparticles was enhanced by the addition of chitosan to its structure. These results suggest that BGN/CH hybrid scaffold can also serve for drug delivery and appear to be a promising biomaterial for bone tissue engineering applications.

Figures Tables

  Gupta, Mahor, Khatri, Goyal, & Vyas, 2006; Jayakumar, Nwe, Tokura, & Tamura, 2007; Jayakumar, Prabaharan, Reis, & Mano, 2005; Jayakumar, Reis, & Mano, 2006; Jayakumar, Selvamurugan, Nair, Tokura, & Tamura, 2008; Muzzarelli, 2009; Muzzarelli et al., 1988). Its chemical composition, which resembles a major component of the bone and cartilaginous tissue, encourages the cell adhesion. Thinks to its cationic nature, chitosan can form complexes with anionic macromolecules such as glycosaminoglycan, which regulate the cytokines and growth factors activity. Its contribution on cell proliferation and differentiation was evidenced (Aranaz et al., 2009; Di Martino, Sittinger, & Risbud, 2005; Şenel & McClure, 2004; Seol et al., 2004). Several synthetic materials such as calcium phosphate in the form of hydroxyapatite (Jayakumar & Tamura, 2006; Jiang, Nair, & Laurencen, 2006; Kong et al., 2005; Zhang et al., 2008; Zhao, Grayson, Ma, Bunnell, & Lu, 2006), or ß-tricalcium phosphate, or calcium phosphate and geopolymers (Takahashi, Yamamoto, & Tabata, 2005; Yin et al., 2003; Zheng et al., 2007) pure, doped with atomic elements or associated with organic molecules have been investigated. Previous studies demonstrate the good effect of the chitosan/bioactive glass association in the improvement of the biological and chemical properties of the obtained composite. In fact, chitosan through its chemical nature approves the cell attachment and bioactive glass enhances the chemical property of this composite (Dorj, Park, & Kim, 2012; Hunger, Donius, & Wegst, 2013). Bioactive glass represents a good candidate for biomedical devices thanks to several properties such as biocompatibility, bioactivity, and its ability to form good chemical links between the biomaterial and the surrounding tissue (Berthiaume, Maguire, & Yarmush, 2011; Jones, 2013; Rahaman et al., 2011). Our previous works have been based on the preparation of bioactive composite glass and chitosan biopolymer (17%) by the freeze-drying process. Through their in vivo experiments, we studied its antioxidative performance and its effect of the generated porosity in the resorption and in the osseointegration of the obtained bio composite (Bui, Oudadesse, Le Gal, Merdrignac-Conanec, & Cathelineau, 2012; Jebahi et al., 2014; Oudadesse et al., 2013).

  They were based on the introduction of porogen leaching in the structure of the material (Chen, Ushida, & Tateishi, 2000; Chen, Ushida, & Tateishi, 2001; Ma, Wang, He, & Chen, 2001), the release of CO 2 (Harris, Kim, & Mooney, 1998; Mooney, Baldwin, Suh, Vacanti, & Langer, 1996), 3D printing (Park et al., 1997), and phase separation mechanisms (Han, 2000; Nam & Park, 1999; Schugens, Maquet, Grandfils, Jerome, & Teyssie, 1996a; Schugens, Maquet, Grandfils, Jerome, & Teyssie, 1996b; Whang, Thomas, Healy, &

FIGURE 3 (

 3 FIGURE 3(a, b) Scanning electron micrograph (SEM) showing the macroporous structure of bioactive glass nanoparticle (BGN)/chitosan (CH) composite scaffold (a) and the dispersion of BGN in the matrix (b). Pore size is about 200 μm (b, white arrows)

FIGURE 4X -

 4X FIGURE 4X-ray diffraction (XRD) pattern of (a) bioactive glass nanoparticle (BGN), (b) chitosan, and (c) BGN/CH composite scaffold

FIGURE 6Fourier -

 6Fourier FIGURE 6Fourier-transform infrared spectroscopy (FTIR) spectra of (a) bioactive glass nanoparticle (BGN), (b) chitosan, and (c) BGN/CH composite scaffold

FIGURE 8 (

 8 FIGURE 8(a, b) Scanning electron micrograph (SEM) showing the structure of bioactive glass nanoparticle (BGN)/chitosan (CH) composite prepared with 2 M (a) and 0.5 M (b) of acetic acid concentration

FIGURE 9X -FIGURE 11 (FIGURE 12 (

 9X1112 FIGURE 9X-ray diffraction (XRD) pattern of bioactive glass nanoparticle (BGN)/chitosan (CH)composite scaffolds before and after soaking 1, 3, and 7 days in simulated body fluid (SBF)

TABLE 1Comparison

 1Comparison between ion concentrations (mM) in SBF and in human blood plasma

		Na +	K +	Ca 2+	Mg 2+	Cl -	HCO 3 -	HPO 4 2-
	SBF	142	5	2.5	1.5	148.8	4.2	1
	Blood	142	5	2.5	1.5	103	27	1
	plasma

TABLE 2Chemical

 2Chemical

composition of the phosphate-buffered saline (PBS)

medium NaCl KCl Na 2 HPO 4 KH 2 PO 4

	Reagent	137	2.7	10	1.8
	concentration
	(mM) in PBS

TABLE 3Surface

 3Surface

	area and porosity volume obtained by Brunauer-Emmett-Teller (BET) for
	the different bioactive glass nanoparticle (BGN)/chitosan (CH) composite scaffolds
	BGN/CH composite	Surface area (m 2 /g)	Porosity volume (mm 3 /g)
	BGN 20/CH	26.6 ± 0.4	7.60 ± 0.03
	BGN 40/CH	25.3 ± 0.3	6.90 ± 0.04
	BGN 60/CH	20.6 ± 0.4	6.70 ± 0.08
	BGN 80/CH	13.8 ± 0.3	6.10 ± 0.08
	3.3Effect of the acetic acid concentration on the structural behavior
	of BGN/CH hybrid scaffold

ACKNOWLEDGMENTS

The authors gratefully acknowledge François Cheviré and Franck Tessier for the X-ray diffraction analysis, Francis Gouttefangeas, Loic Joanny, and Christophe Calers (CMEBA) for scanning electron microscopy analysis, Nathalie Herbert and Odile Merdrignac for the BET analyses. The authors would like to thank Université de Rennes 1 and CNRS, France for their funding support.

CONFLICT OF INTEREST

The authors declare no potential conflict of interest.


W Argyle

M Sala

M Scardia

J.-L Prieur

L Pansecchi

R W Argyle

Speckle observations with PISCO in Merate: X. Astrometric measurements of visual binaries in 2009

Keywords: binaries, close -binaries, visual -astrometry -techniques, interferometric -individual (ADS 2377, ADS 8035,

published or not. The documents may come     Speckle observations with PISCO in Merate. X. Astrometric measurements of visual binaries in 2009

Introduction

This paper deals with the results of speckle observations of visual binary stars made in Merate (Italy) in 2009 with the Pupil Interferometry Speckle camera and COronagraph (PISCO) on the 102 cm Zeiss telescope of INAF -Osservatorio Astronomico di Brera (OAB, Brera Astronomical Observatory). It is the tenth of a series (Scardia et al. 2005, 2006[START_REF] Van Leeuwen | Hipparcos, the new reduction of the raw data[END_REF], 2008a, Prieur et al. 2008, Scardia et al. 2009, Prieur et al., 2009, Scardia et al., 2010, Prieur et al., 2010, herein: Papers I to IX), whose purpose is to contribute to the determination of binary orbits. PISCO was developed at Observatoire Midi-Pyrénées (France) and first used at Pic du Midi from 1993 to 1998. It was moved to Merate in 2003 and used there since.

We briefly describe our observations in Sect. 2. Then we present and discuss the astrometric measurements in Sect. 3. Finally in Sect. 4 we propose new revised orbits for ADS 8035, 9982, 11484 and MLR 198, partly derived from those observations, and discuss the estimated values for the masses of those systems.

Observations and description of the observing list

The observations were carried out with the PISCO speckle camera with the ICCD (Intensified Charge Coupled Device) detector belonging to Nice University (France). This instrumentation is presented in Prieur et al. (1998) and our observing procedure is described in detail in Paper VI.

The description of our observing list can be found in our previous papers (e.g., Paper VI). It basically includes all the visual binaries for which new measurements are needed to improve their orbits, that are accessible with our instrumentation.

The distribution of the angular separations measured in this paper is displayed in Fig. 1a and shows a maximum for ρ ≈ 0 ′′ .7. The largest separation of 4 ′′ .6 was obtained for ADS 6175. The smallest separation was measured for HU 66AB (ADS 11344), with ρ = 0 ′′ .18. This is rather close to the diffraction limit ρ d = λ/D ≈ 0 ′′ .13 for the Zeiss telescope (aperture D = 1.02 m) and the R filter (λ = 650 nm).

Likewise, the distribution of the apparent magnitudes m V and of the difference of magnitudes ∆m V between the two components are plotted in Figs. 1b and1c, respectively. The telescope aperture and detector sensitivity lead to a limiting magnitude of about Distribution of the angular separations of the 345 measurements of Table 1 (a), of the total visual magnitudes (b) and of the differences of magnitude between the two components of those binaries (c). HR diagram of the binaries measured in Table 1, for which Hipparcos parallaxes were obtained with a relative error smaller than 50% (i.e., 251 objects). m V = 9 (Fig. 1b) and a limiting ∆m V of about 4.0 (Fig. 1c).

Using the Hipparcos parallaxes, we were able to construct the HR diagram of those binaries, which is displayed in Fig. 2. We only plotted the objects for which the relative uncertainty on the parallax was smaller than 50%. It can be seen that a large part of the HR diagram is covered by our observation program. In the future we would like to acquire a more sensitive detector in order to observe fainter (and cooler) main sequence stars.

Astrometric measurements

The astrometric measurements of the observations made in 2009 are displayed in Table 1. For each object, we report its WDS name (Washington Double Star Catalogue, Mason et al. 2010, hereafter WDS Catalogue) in Col. 1, the official double star designation in Col. 2 (sequence is "discoverer-number"), and the ADS number in Col. 3 [START_REF] Aitken | New General Catalogue of Double Stars[END_REF] when available. For each observation, we then give the epoch in Besselian years (Col. 4), the filter (Col. 5) and the focal length of the eyepiece used for magnifying the image (Col. 6), the angular separation ρ (Col. 7) with its error (Col. 8) in arcseconds, and the position angle θ (Col. 9) with its error (Col. 10) in degrees. In Col. 11, we report some notes and some information about the secondary peaks of the auto-correlation files (e.g. diffuse, faint or elongated). For the systems with a known orbit, the (O-C) (Observed minus Computed) residuals of the ρ and θ measurements are displayed in Cols. 13 and 14, respectively. The corresponding authors are given in Col. 12, using the bibliographic style of the "Sixth Catalogue of Orbits of Visual Binary Stars" (Hartkopf & Mason, 2010, hereafter OC6). Unless explicitly specified, the measurements refer to the AB components of those systems. In Col. 14, the symbol Q indicates that there was a quadrant inconsistency between our measures and the orbital elements published for this object.

The characteristics of the V , R and RL filters used for obtaining those measurements are given in Table 2 of Paper IX. Some objects were observed with no filter because they were too faint. This is indicated with W (for "white" light) in the filter column (Col. 5 of Table 1). In that case, the bandpass and central wavelength correspond to that of the ICCD detector (see Prieur et al., 1998).

As for the other papers of this series, we interactively processed all the auto-correlation files computed in real time during the observations and obtained a series of measurements with different background estimates and simulated noise. The measures and errors displayed in Table 1 were derived from the mean values and the standard deviation of those multiples measurements (see Paper III for more details). The average values of the errors of the 345 measurements reported in this table are 0 ′′ .011 ± 0 ′′ .007 and 0 • .57 ± 0 • .39 for ρ and θ, respectively.

There is only one unresolved object: COU 773. This is not really surprising since the ephemeris of Couteau's orbit (1999) gives ρ = 0 ′′ .189, which is close to the diffraction limit of the Zeiss telescope. In this data set, the closest separation we managed to resolve was 0 ′′ .18, for HU 66AB (see Sect. 2).

Multiple systems

ADS 719: this object is known as a wide triple system. In 2009, we measured the AB and AC pairs, with ρ = 1 ′′ .53 and ρ = 3 ′′ .95, respectively.

ADS 2377 (new discovery): In the WDS catalogue there are two couples associated to ADS 2377: STT 50 AB (our target) and HJ 2172 AC, much wider (28 ′′ ) and out of the field of view of our detector. Furthermore, the C component is very weak (m V = 14). The secondary peaks of the auto-correlation are clearly double in our observations made in 2009.081 (see Fig. 3). This suggests the presence of a new component, not visible in our previous observations of 2005 (Paper III). Since the auto-correlation peaks are symmetric, and since it was not possible to reconstruct the image with bispectral methods (see an example in Paper VI), we cannot decide whether the new component is associated to A or B. Therefore, we provisionally assume that it is orbiting A and propose to call the new couple SCA 171Aa,Ab. The R magnitude of this component is estimated at 9.0-9.2.

ADS 11344: this object is known as a triple system. We already observed it in 2004.690 (Paper II), and in 2007.671, when we obtained an image of the autocorrelation with clear double secondary peaks (Paper VIII). In 2009, we also obtained similar peaks and could measure the AB and AC components. The innermost peaks correspond to STT 351AC and the outermost ones to HU 66BC. Finally, each couple composed by the big and small secondary peaks correspond to HU 66AB. (see Paper VIII).

ADS 11635: two known couples could be measured for this object: STF2382 AB and STF2383 Cc-D.

ADS 11077: in 2005 we discovered a new component with rho=0.228 and theta=50.2 (Paper IV), which was confirmed in 2007 (Paper VIII). This pair is now reported as "SCA170Aa,Ab" both in the WDS and in the "Fourth Catalogue of Interferometric Measurements of Binary Stars" (Hartkopf et al. 2010, hereafter IC4). Unfortunately, we cannot detect this companion in the data obtained in August 2009, which are of poor quality, with a fuzzy autocorrelation.

ADS 10270 and ADS 13572: the auto-correlation files show extra secondary peaks in both cases, which suggest the existence of possible new components. However we cannot rule out yet that there are mere artefacts. Further observations are needed to confirm those findings.

Quadrant determination

As our measurements were obtained from the symmetric auto-correlation files, the θ values first presented a 180 • ambiguity. To resolve this ambiguity and determine the quadrant containing the companion, we have used Aristidi et al. (1997)'s method, by analysing the restricted triple correlation (RTC hereafter) files that were computed in real time during the observations. For the couples with the largest separations, a straightforward determination could be done when the companions were visible in the long integration files.

As a result, in Table 1, we are able to give the unambiguous (i.e. "absolute") position angles of 280 out of 345 measurements, i.e. 81% of the total. They are marked with an asterisk in Col 9. Otherwise, our angular measurements were reduced to the quadrant reported in the WDS catalogue, which is extracted from the IC4.

Our "absolute" θ values are consistent with the values tabulated in WDS for all objects except for ADS 710, 2980, 8820, 9498, 9530, 10905, 11558 and 14839. We display some parameters of all those objects in Table 2. In Col. 2, we indicate the quadrant (Q) we found with the RTC, using the usual convention of numbering them from 1 to 4 to indicate the North-East, South-East, South-West and North-West quadrants, respectively. In Col. 3 we recall the filter we have used (W indicates the absence of filter: the corresponding central wavelength is close that of the R filter). In Col. 4 and 5, we give the differences of magnitude between the two components and the global spec- Note: In column 9, the exponent * indicates that the position angle θ could be determined without the 180 • ambiguity.

(O-C) ∆θ(O-C) (mm) ( ′′ ) ( ′′ ) ( • ) ( • ) ( ′′ ) ( • ) 11037+6145 BU1077 8035
In column 14, the exponent Q indicates discrepant quadrants between our measurements and the published orbits. tral types found in the WDS catalogue, and the French SIMBAD astronomical data base. For all the discrepant objects, there is a good contrast between the two secondary peaks of the RTC, which is a good indication of the validity of our quadrant determination.

Except for ADS 14839, the small value of ∆m V can account for the difficulty of measuring the quadrant for those binaries. However, the measurements from other observers reported in IC4 were all obtained in B or V , whereas we observed in R (or W which is similar). A quadrant inversion between V and R is likely, when the two stars have a different spectral type (e.g. blue primary and red secondary). This would well explain a different quadrant measurement in V (in the IC4) and in R (with PISCO).

For ADS 14839, there is instead a rather large difference of magnitude between the components (1.6 mag). Our estimation of Q=3 seems reliable in the RTC and is consistent with 23 out of the 26 measurements made since 2000, reported in IC4, and with our previous quadrant determination of 2004.950.

Comparison with published ephemerides

The (O -C) (Observed minus Computed) residuals of the measurements for the 155 systems with a known orbit in Table 1 are displayed in Cols. 13 and 14 for the separation ρ and position angle θ, respectively.

Those residuals were computed with a selection of valid orbits found in the "master" file of the OC6 catalogue. We did not always use the most recent orbits since sometimes older orbits led to equivalent or even smaller residuals. We think that the publication of many new orbits is not always scientifically justified.

For ADS 8035, 9982, 11484 and MLR 198, we also give the residuals obtained with our new orbits presented in Sect. 4, for comparison.

Fig. 4 shows that the residuals have a rather large scatter that can be explained by the (old) age of many orbits. The mean values computed with the residuals of Table 1 Fig. 4 Residuals of the measurements of Table 1 computed with the published orbits.

are < ∆ρ O-C >= 0 ′′ .00 ± 0 ′′ .04 and < ∆θ O-C >= -0 • .2 ± 2 • .1 (
for those offsets provide an additional validation of our calibration made with a grating mask (see Paper III).

In the following, we examine the cases of MLR 198, ADS 8094 and ADS 10429 that appear with the largest residuals in Fig. 4.

ADS 8094: Hopmann's orbit (1970) leads to large residuals of (0 ′′ .40, 15 • .5) with our measurement of 2009.396. Clearly this orbit is wrong, as already pointed out in Papers III and VIII. The motion appears to be rectilinear, and is, in any case, too short to attempt a meaningful orbital analysis at present.

ADS 10429 Olevic et al.'s orbit (1993) leads to rather large residuals of (-0 ′′ .22, 1 • .5). The arc of orbit is still short and the measurements have a large dispersion. The derivation of new valid orbital parameters is not yet possible.

MLR 198 the last orbits, either from Hartkopf & Mason (2001) or from Seymour et al. (2002), lead to very large residuals in θ (see Fig. 4). We propose a new orbit in the next section.

4 Revised orbits of ADS 8035, 9982, 11484 and MLR 198 In this section we present the new orbits we have computed for ADS 8035, 11484 and MLR 198, which have large residuals in Table 1, and for ADS 9982, to take advantage of all the observations made after 1962.

We have followed the same method for those four objects. Using our last measurements with PISCO and the other available observations contained in the data base maintained by the United States Naval Observatory (USNO), we first computed the preliminary or-bital elements with the analytical method of [START_REF] Kowalsky | Procès-verbaux de l'Université Impériale de Kasan[END_REF]. We then used them as initial values for the least-squares method of Hellerich (1925). When convergence was achieved, Hellerich's method led to an improvement of the orbital elements (with the exception of the major axis) and to an estimation of the corresponding errors. The final value of the major axis was then set to the value that minimized the residuals in separation of Hellerich's solution.

The final orbital elements are presented in Table 3. The description of the format of the tables contained in this section can be found in Papers VI and VII. The errors reported for ADS 8035, 9982 and MLR 198 were obtained by Hellerich's least-squares method. For ADS 11484, this method failed to converge, which explains the absence of errors for this orbit.

The corresponding (O -C) residuals, restricted to the last observations for reasons of space, are given in Tables 4,5, 6 and 7 for ADS 8035, 9982, 11484 and MLR 198, respectively. In the last column, we report the name of the observer, using the US Naval Observatory convention.

The ephemerides for 2010-2021 are presented in Table 8. The apparent orbits are shown in Fig. 5 as solid lines. The observational data used for the calculation of the orbital elements are plotted as small crosses or, in the case of PISCO observations, as filled circles. The orientation of the graphs conforms to the convention adopted by the observers of visual binary stars. For each object, the location of the primary component is indicated with a big cross. The straight line going through this point is the line of apsides. An arrow shows the sense of rotation of the companion.

In Table 9, we present some physical parameters of those systems. The visual magnitudes (col. 3) and the spectral types (col. 4) were extracted from the SIMBAD data base. For ADS 8035, we also added the classification K0III+F0V from [START_REF] Eggleton | [END_REF]. The dynamical parallaxes derived from our orbital elements are presented in col. 5. Except for ADS 8035 (see in Sec. 4.1), those values were obtained with Baize & Romani (1945)'s method, using our revised formulae presented in Scardia et al. (2008b). In col. 6, we report either the Hipparcos parallaxes from ESA (1997) or the revised values from van Leeuwen (2007), as indicated in col. 10. In cols. 8 and 9, we give the corresponding linear sizes of a and M total , respectively, that were computed from our orbital elements and the Hipparcos parallaxes.

New orbit of ADS 8035, BU 1077

This couple was discovered by S.W. Burnham in 1889 with the 36-inch Lick refractor. The primary component of ADS 8035 is a famous bright star (Dubhe, α UMa, HR 4301). In visual observations, this object appears as a triple system, with a faint C component (with m V = 7.1) at 380 ′′ from the A-B pair. Spectroscopic measurements have shown that the C component was a spectroscopic binary (F8, P = 6.035 d, e = 0.09). The A component is a red giant, with a significant proper motion. Its spectral classification shows some uncertainties: it is K0Iab in SIMBAD, G9III in the WDS, and K0III in De Medeiros & Mayor (1999). It is a slow rotator with v sin i = 3.7 km.s -1 (Fekel, 1997). Its diameter was estimated at ∼ 7 mas, corresponding to 0.25 AU, with long-base interferometry by Nordgren et al. (2001) and [START_REF] Mozurkewich | [END_REF].

Our new orbit was computed using our measures made in 2009 (see Table 1) and in 2010 (four measures not yet published), and the 63 other measures available in the USNO data base. It should be mentioned that 18 out of the 19 observations made after 1994 were obtained by our group. The standard deviations of the residuals are 2 • .5 and 0 ′′ .05 for θ and ρ, respectively.

Since the primary star is a giant star, the dynamical parallax cannot be computed with Baize-Romani's method which is based on the mass-luminosity relation. So we derived it in Table 9 from Kepler's third law:

̟ dyn = a (M 1 + M 2 ) 1/3 P 2/3
(1)

where M 1 and M 2 are the component masses in M ⊙ , P the period in years, and a the semi major axis in arcseconds.

In Table 9, we have reported the two values of ̟ dyn obtained when using the spectral classification of K0III+F0V given by [START_REF] Eggleton | [END_REF] or the alternative combination of K0Iab+F0V that was derived from the K0Iab classification found in SIMBAD. We assumed theoretical masses of 1.1 M ⊙ , 1.6 M ⊙ and 6 M ⊙ , for K0III, F0V and K0Iab stars, respectively [START_REF] Drilling | Allen's Astrophysical Quantities[END_REF]. The Hipparcos parallax is close to the average of those two values, which suggests an intermediary combination such as K0II+F0V for this binary system.

Similarly, the systemic mass of about 5.6±0.8 M ⊙ derived from the relation (1) with our orbital elements and the Hipparcos parallax (see Table 9) lies in the middle of the interval bounded with 2.7 M ⊙ and 7.6 M ⊙ , that correspond to the combinations of K0III+F0V and K0Iab+F0V, respectively.

A classification as K0II for the primary star would also be supported by the photometry. Indeed, from the Hipparcos parallax and m V = 1.8 (from SIMBAD), we derive an absolute magnitude of M V ≈ -1.1 for the primary star (the contribution of the companion is negligible since ∆m V ≈ 3.0, as reported in the WDS). This value is also intermediary between the values of M V = -6.0 and M V = 0.7 that are expected for typical K0Iab and K0III stars, respectively. This couple was measured for the first time by F.G.W. Struve, on May 18th 1829, but was well observed only after the end of the XIXth century. It is made of two K4V stars with similar magnitudes: m V = 9.5 and 9.9. This system has a significant proper motion and is close to the sun (distance of about 26 pc). Only a few orbits have been computed for this system: Aitken (1914), Comstock (1918), [START_REF] Woolley | [END_REF] and [START_REF] Heintz | [END_REF]. Heintz' orbit is still good, but very old.

From the 301 measurements obtained since 1830, we derived the new orbital elements reported in Table 3. The standard deviations of the residuals are 1 • .7 and 0 ′′ .08 for θ and ρ, respectively.

Our new orbit well fit the data, and the uncertainties on the elements are small. The systemic mass is compatible with the theoretical value of 1.4 M ⊙ [START_REF] Drilling | Allen's Astrophysical Quantities[END_REF] expected for a couple of two K4V stars. The dynamical parallax computed with our formula of Scardia et al. (2008b) is also in good agree-

New orbit of ADS 11484, STT 357

This binary was discovered by O. Struve with the 38 cm Merz-Mahler refractor of Poulkovo Imperial Observatory between August 1841 and December 1842. From then, its motion was well monitored, except during the period 1925-1935, but the measures have generally a large scatter. To our knowledge, only two orbits have been computed for ADS 11484, by [START_REF] Florsch | [END_REF] and Valbousquet (1981). The orbit of Valbousquet (1981) is still valid, but becomes to be old now.

We computed a new orbit from the 124 available measures. On average, those measures were of poor quality, which impeded the convergence of Hellerich's least-square method. The solution we found seems satisfactory but is still preliminary. The mean standard deviation of the residuals is 3 • .3 for θ and 0 ′′ .06 for ρ.

With the Hipparcos parallax of ESA (1997), the systemic mass of 4.5 M ⊙ is in good agreement with the theoretical value of 5 M ⊙ for a system of two A2V stars. With van Leeuwen's revised parallax, the mass would be 8.7 M ⊙ , which is slightly too large (but the uncertainties are also very large).

The dynamical parallax is 5.6 mas is in very good agreement with the Hipparcos parallax of ESA (1997).

New orbit of MLR 198, HD 151746

This couple was discovered by P. Muller with the 50 cm refractor of Nice Observatory in 1971 during his survey of the northern hemisphere between +52 • and +90 • in declination (Muller, 1971).

This object is also known as an Am star, that we studied as such in Prieur et al. (2006), where we found that HD 151746 was an SB1 spectroscopic binary and determined its spectroscopic orbit. This orbit has a very short period (4.8 days) and a zero eccentricity.

From the 31 available measures of MLR 198 made since 1971, we derived an orbit with a long period, about twice as long as the period of Seymour et al.'s orbit (2002). Convergence was achieved with Hellerich's least-square method. Our solution well fit the data and the mean standard deviation of the residuals is 2 • .9 for θ and 0 ′′ .02 for ρ.

Our solution leads to a plausible value of 4.4 M ⊙ for the systemic mass with the Hipparcos parallax of ESA (1997), since the theoretical mass value of an A2 star is about 2.5 M ⊙ [START_REF] Drilling | Allen's Astrophysical Quantities[END_REF]. With van Leeuwen (2007)'s revised parallax, the systemic mass would be only 3.1 M ⊙ , which is slightly underestimated. The dynamical parallax derived from our orbital parameters is in very good agreement with the Hipparcos parallax of ESA (1997).

Conclusion

In 2009, we obtained 345 new measurements of 259 visual binaries with PISCO in Merate, with an average accuracy of 0 ′′ .011 for the angular separation and 0 • .6 for the position angles. The total number of measurements made in Merate since 2004 now exceeds 2100. This work is thus a good contribution to the continuing monitoring of long period visual binary systems, which is important for refining systemic stellar masses.

We have found a possible new close component for ADS 2377, which would be a new quadruple star system.

We used then the measurements reported here to find some orbits that needed to be revised. We then presented the new orbital elements that we obtained for ADS 8035, 9982, 11484 and MLR 198. The values of the masses derived from those elements are compatible with the theoretical values. For ADS 8035, our orbital elements suggest a spectral classification of K0II+F0V for this system. The dynamical parallaxes derived from those elements are also in good agreement with the Hipparcos parallaxes.

  Fig. 1Distribution of the angular separations of the 345 measurements of Table1(a), of the total visual magnitudes (b) and of the differences of magnitude between the two components of those binaries (c).

  Fig.2HR diagram of the binaries measured in Table1, for which Hipparcos parallaxes were obtained with a relative error smaller than 50% (i.e., 251 objects).

Fig. 3

 3 Fig. 3Auto-correlation showing the possible new component (small peaks) in the multiple system ADS 2377 (see text for details).

Fig. 5

 5 Fig. 5 New orbits of ADS 8035 (a), ADS 9982 (b), ADS 11484 (c) and MLR 198 (d).

Table 1

 1 Measurements of binaries with PISCO in 2009 (begin.).

	WDS	Name	ADS Epoch Fil. Eyep.	ρ	σρ	θ	σ θ Notes	Orbit	∆ρ(O-C) ∆θ(O-C)
				(mm) ( ′′ )	( ′′ )	( • ) ( • )		( ′′ )	( • )
	00134+2659 STT2	161 2009.960 R	10 0.415 0.003 161.3 * 0.4	Sca2000b	-0.03	-1.3
	00210+6740 HJ1018	283 2009.960 R	20 1.683 0.008 86.8 * 0.3	Mlr1957b	0.09	0.2
	00218+6628 STT7	296 2009.960 W	20 0.886 0.008 126.9 * 0.7
	00442+4614 STF52	616 2009.957 W	20 1.373 0.008	3.0 * 0.3
	00481+2533 HO306	662 2009.034 R	20 1.458 0.015 159.3 * 0.6
	00504+5038 BU232	684 2009.034 R	20 0.880 0.008 250.4 0.9	Sca2008a	0.02	-1.5
	00516+6859 BU781	692 2009.062 W

Table 1

 1 Measurements of binaries with PISCO in 2009 (cont.).

	WDS	Name	ADS Epoch Fil. Eyep.	ρ	σρ	θ	σ θ Notes	Orbit	∆ρ

Table 1

 1 Measurements of binaries with PISCO in 2009 (cont.). Measurements of binaries with PISCO in 2009 (cont.).

				2009.385 V	10 0.557 0.004 25.9 * 1.2	Sca2005a	-0.02	-5.1
	"	"	"	"	"	"	"	"	" "	Hei1963a	0.02	1.2
	"	"	"	"	"	"	"	"	" "	This paper	-0.01	0.4
	11136+5525 A1353	8092 2009.207 R	20 0.577 0.008 211.4 * 0.4	Hei1997	0.02	0.2
	11137+2008 STF1517	8094 2009.396 R	10 0.638 0.003 317.6 0.9	Hop1970	0.40	15.5
	11182+3132 STF1523	8119 2009.265 R	20 1.594 0.008 215.0 * 0.3	Hei1996b	-0.00	-0.2
	11190+1416 STF1527	8128 2009.207 R	10 0.316 0.007 172.6 0.6	Pru2009	0.04	-1.3
	"	"	" 2009.265 R	10 0.311 0.003 174.6 0.6	Pru2009	0.03	-0.2
	"	"	" 2009.330 R	10 0.317 0.005 174.9 0.3	Pru2009	0.04	-0.9
	"	"	" 2009.349 R	10 0.302 0.003 175.4 * 0.3	Pru2009	0.03	-0.7
	"	"	" 2009.382 R	10 0.319 0.004 175.2 0.9	Pru2009	0.05	-1.4
	"	"	" 2009.385 R	10 0.323 0.003 175.3 0.6	Pru2009	0.05	-1.4
	"	"	" 2009.390 R	10 0.313 0.003 175.1 0.7	Pru2009	0.04	-1.6
	"	"	" 2009.396 R	10 0.322 0.005 175.5 * 0.3	Pru2009	0.05	-1.3
	11239+1032 STF1536	8148 2009.331 R	20 1.930 0.014 100.9 * 0.3	Sod1999	-0.03	-0.1
	11308+4117 STT234	8189 2009.265 R	20 0.489 0.008 171.2 1.1	Doc2001f	0.01	0.3
	11323+6105 STT235	8197 2009.265 R	20 0.770 0.008 20.5 * 0.3	Hei1990c	-0.01	2.0
	11363+2747 STF1555	8231 2009.390 R	10 0.729 0.004 148.9 * 0.4	Doc2007i	0.03	-0.3
	11388+6421 STF1559	8249 2009.391 R	20 1.957 0.010 322.9 * 0.3
	11390+4109 STT237	8252 2009.391 R	20 2.024 0.014 244.1 * 0.5	Sey2002	0.02	-0.9
	11486+1417 BU603	8311 2009.396 R	20 1.025 0.017 335.0 * 0.9	Sta1980a	-0.05	1.5
	11520+4805 HU731	8325 2009.391 W	20 1.094 0.008 308.6 * 0.3 Elongated Hrt2008	-0.02	-0.1
	11537+7345 BU794	8337 2009.391 R	20 0.524 0.011 50.3 * 1.0	Sod1999	0.03	0.1
	12108+3953 STF1606	8446 2009.396 R	20 0.444 0.014 157.3 * 1.2	Msn1999a	-0.02	2.5
	12244+2535 STF1639	8539 2009.396 R	20 1.788 0.009 323.9 * 0.3	Ole2000b	0.00	0.2
	"	"	"	"	"	"	"	"	" "	All1951	0.05	1.1
	12306+0943 STF1647	8575 2009.396 W	20 1.279 0.011 246.7 * 0.6	Hop1970	0.02	-3.2
	12409+0850 STF1668	8625 2009.382 R	20 1.131 0.008 187.1 0.6
	12417-0127 STF1670	8630 2009.330 R	20 1.231 0.008 28.6 * 0.3	Sca2006b	-0.01	0.7
	"	"	" 2009.382 R	20 1.244 0.008 28.3 * 0.7	Sca2006b	-0.01	0.8
	"	"	" 2009.385 R	20 1.258 0.009 28.6 * 0.6	Sca2006b	-0.00	1.1
	"	"	" 2009.448 RL 20 1.258 0.009 27.2 * 0.5	Sca2006b	-0.01	0.1
	12592+8256 STF1720	8738 2009.385 W	20 1.622 0.014 329.3 * 0.5 Elongated
	13007+5622 BU1082	8739 2009.382 R	20 1.098 0.008 99.0 * 0.3	Sca2005a	-0.13	2.3
	"	"	"	"	"	"	"	"	" "	Sod1999	-0.01	-2.3
	13048+7302 BU799	8772 2009.385 R	20 1.367 0.012 265.7 * 0.3
	13064+2109 COU11	-2009.385 R	20 1.693 0.008 315.8 * 0.4
	13128+4030 A1606	8820 2009.391 W	20 1.290 0.008 196.3 * 0.4
	13375+3618 STF1768	8974 2009.391 R	20 1.750 0.010 96.7 * 0.3	Sod1999	0.02	0.0
	"	"	"	"	"	"	"	"	" "	Sta1976b	-0.01	0.9
	14131+5520 STF1820	9167 2009.505 R	20 2.694 0.013 119.7 * 0.3	Kiy1998	0.06	-1.4
	14531+7811 HU908	9445 2009.541 R	20 1.536 0.008 237.4 * 0.4
	14568+7050 STF1905	9460 2009.541 W	20 2.826 0.014 161.0 * 0.3
	15038+4739 STF1909	9494 2009.538 R	20 1.695 0.008 58.9 * 0.4	Sod1999	0.04	-0.3
	15056+1138 STF1907	9498 2009.538 W	20 0.886 0.008 169.9 * 1.7
	15116+1007 A1116	9530 2009.538 W	20 0.843 0.018 233.0 * 1.1
	15232+3017 STF1937	9617 2009.391 R	10 0.564 0.003 160.6 * 0.3	Msn1998c	-0.01	-0.1
	"	"	"	"	"	"	"	"	" "	Mut2010b	-0.00	-0.1
	15245+3723 STF1938Ba,Bb 9626 2009.391 R	20 2.276 0.011	5.9 * 0.3	Sca1986b	0.05	0.2
	15246+5413 HU149	9628 2009.541 R	20 0.658 0.011 270.8 0.4
	15264+4400 STT296	9639 2009.599 W	20 2.099 0.019 274.8 * 0.3 Elongated
	15278+2906 JEF1	-2009.541 R	10 0.203 0.008 131.4 * 1.7 Diffuse	Sod1999	-0.01	-1.6
	"	"	"	"	"	"	"	"	" " "	Mut2010b	-0.00	-0.3
	15329+3122 COU610	-2009.599 R	20 0.825 0.008 198.7 * 0.7
	15360+3948 STT298	9716 2009.541 R	20 1.058 0.008 177.9 * 0.5	Cou1966c	0.01	0.0
	16133+1332 STF2021Aa-B 9969 2009.593 R	20 4.091 0.020 356.1 * 0.3	Hop1964b	0.01	1.0

* 0.5

Table 1

Table 1

 1 Measurements of binaries with PISCO in 2009 (cont.).

	WDS	Name	ADS Epoch Fil. Eyep.	ρ	σρ	θ	σ θ Notes	Orbit	∆ρ(O-C) ∆θ(O-C)
						(mm) ( ′′ )	( ′′ )	( • ) ( • )		( ′′ )	( • )
	20198+4522 STT406	13723 2009.818 R	20 0.289 0.008 102.1 1.4	Hei1976	-0.12	-1.5
	20303+1054 BU63	13920 2009.818 R	20 0.907 0.008 349.6 * 0.4
	20370+1203 STF2701 14063 2009.757 W	20 2.042 0.010 221.1 * 0.4
	20375+1436 BU151	14073 2009.757 R	10 0.374 0.003 21.7 * 0.5	Alz1998a	-0.01	-0.2
	"	"	"	"	"	"	"	"		" "	Mut2010e	-0.01	-0.0
	20423+5723 BU152	14196 2009.861 R	20 1.180 0.008 82.4 * 0.6
	20449+1219 STF2723 14233 2009.818 R	20 1.038 0.009 136.1 * 0.5
	20450+1244 BU64	14238 2009.818 W	20 0.664 0.010 353.1 0.5	Bdl2007a	0.01	-0.4
	20471+2525 BU364	14286 2009.818 W	20 0.788 0.008 70.4 0.3
	20478+0600 BU65	14293 2009.818 RL 20 1.491 0.008 198.9 * 0.5
	20481+2727 BU66	14312 2009.747 W	20 1.051 0.012 168.3 * 0.3
	20486+5029 BU366	14331 2009.747 W	20 1.481 0.008 129.6 * 0.3
	20511+0623 STF2730 14359 2009.741 W	20 3.307 0.020 333.2 * 0.3
	20531+2909 STT417	14397 2009.741 W	20 0.882 0.008 27.5 * 0.6 Elongated
	20591+0418 STF2737 14499 2009.747 R	10 0.535 0.003 284.8 0.4	Zel1965	0.02	1.2
	20595+5013 BU68	14520 2009.861 W	20 1.922 0.010 148.5 * 0.3
	20598+6152 BU472	14540 2009.861 W	20 0.775 0.008 15.3 * 0.5
	21015+6643 HU959	14578 2009.861 W	20 1.291 0.008 161.3 * 0.3 Elongated
	21055+6210 HU765BC 14634 2009.861 W	20 0.787 0.008 28.0 * 0.8
	21183+3456 BU289	14837 2009.820 W	20 0.795 0.012 127.0 * 0.3
	21186+1134 BU163	14839 2009.757 W	20 0.801 0.008 257.4 * 1.5	Fek1997	0.00	-1.4 Q
	"	"	"	"	"	"	"	"		" "	Ces1991	0.02	0.3
	21199+4307 COU2439	-2009.820 W	20 0.722 0.011 265.4 * 0.9
	21227+5214 HU591	14931 2009.820 W	20 0.725 0.008 128.1 * 0.3
	21237+5518 A1892	14945 2009.820 W	20 0.752 0.008 348.6 * 0.5
	21268+4228 A619	14992 2009.960 W	20 0.747 0.013 59.6 * 0.7
	21446+2539 BU989	15281 2009.940 R	10 0.262 0.003 115.5 * 0.5	Ces1990	-0.01	-0.0
	21523+6306 STF2845 15417 2009.943 W	20 1.974 0.010 173.0 * 0.3
	21555+1053 BU75	15447 2009.861 W	20 0.962 0.008 22.6 * 0.4	Hei1996a	-0.01	0.3
	22257+5631 A1463	15933 2009.957 W	20 0.917 0.008 333.0 * 0.3
	22288-0001 STF2909 15971 2009.820 R	20 2.109 0.011 169.2 * 0.3	Sca2009c	-0.02	-2.5
	"	"	" 2009.941 RL 20 2.137 0.011 168.9 * 0.3	Sca2009c	0.00	-2.6
	"	"	" 2009.957 R	20 2.123 0.011 168.9 * 0.3	Sca2009c	-0.01	-2.6
	22419+2126 STF2934 16185 2009.818 W	20 1.361 0.008 57.6 * 0.3	Hei1981a	0.14	0.7
	22425+3917 BU176	16198 2009.820 W	20 2.565 0.013 53.7 * 0.3
	22485+5409 AG424	16280 2009.818 W	20 2.234 0.011 134.6 * 0.3
	22509+5303 BU1332	16310 2009.821 W	20 1.505 0.008 128.8 * 0.3
	22557+1547 HU987	16373 2009.941 W	20 1.139 0.010 78.0 * 0.3	Bdl2007a	0.05	-1.0
	22569+1151 STF2958 16389 2009.957 RL 20 3.893 0.019 13.9 * 0.3
	23079+7523 STT489	16538 2009.957 RL 20 1.111 0.008 353.1 * 0.9	Sca2009a	-0.01	-2.4
	23133+2205 STF2990 16602 2009.941 W	20 2.536 0.013 55.9 * 0.3 Diffuse
	23340+3120 BU720	16836 2009.957 R	10 0.559 0.003 100.0 * 0.3	Mut2010e	-0.00	-0.7
	23375+4426 STT500	16877 2009.957 R	10 0.464 0.003 10.3 0.7	Zul1981	0.04	-4.3

  rejecting the two outliers of ADS8094 and MLR 198). The small values obtained

	MLR 198
	ADS 8094
	ADS 10429

Table 3

 3 New orbital elements of ADS 8035, 9982, 11484 and MLR 198

	ADS	Ω2000	ω	i	e	T	P	n	a	A	B	F	G
		( • )	( • )	( • )		(yr)	(yr)	( • /yr)	( ′′ )	( ′′ )	( ′′ )	( ′′ )	( ′′ )
	ADS 8035	9.3 232.8 159.9 0.4392 2002.170 44.448 8.0994 0.590 -0.42335 0.37788 0.40964 0.40653
		±8.2 ±7.9 ±3.5 ±0.004 ±0.094 ±0.11 ±0.020 ±0.026
	ADS 9982 14.31 194.74 133.04 0.8104 1907.053 441.8 0.8148 2.380 -2.33241 -0.16843 0.19848 1.67184
		±0.9 ±0.8 ±0.5 ±0.007 ±0.06	±25	±0.05 ±0.04
	ADS 11484 93.8 321.9 124.8 0.317 1968.324 411.1 0.87570 0.511 -0.20620 0.38931 0.20810 0.32982
	MLR 198 169.7 299.4 147.7 0.657 1992.918 54.4 6.61370 0.195 -0.11986 -0.12417 -0.15268 0.10999
		±8.2 ±7.0 ±10.0 ±0.04	±0.04	±4.6 ±0.56 ±0.065

Table 4

 4 ADS 8035: O-C residuals of our new orbit (after 2000.0). The symbol P indicates PISCO measurements.

	Epoch	∆ρ (O-C) ∆θ (O-C) Observer
		( ′′ )	( • )
	2004.213	0.026 P	-1.4 P Sca
	2004.397	0.025 P	0.7 P Sca
	2005.259	0.011 P	-0.2 P Sca
	2005.382	0.007 P	0.2 P Sca
	2005.385	0.006 P	0.5 P Sca
	2006.270	0.009 P	1.4 P Pru
	2006.310	0.003 P	0.7 P Pru
	2007.261	-0.004 P	-0.7 P Pru
	2009.207	-0.001 P	-0.1 P Sca
	2009.382	0.008 P	1.3 P Sca
	2009.385	-0.000 P	0.4 P Sca
	2010.264	-0.006 P	-1.6 P Sca
	2010.324	-0.003 P	-1.9 P Sca
	2010.327	-0.001 P	-1.1 P Sca
	2010.384	-0.004 P	-0.8 P Sca

Table 5

 5 ADS 9982: O-C residuals of our new orbit (after 2000.0). The symbol P indicates PISCO measurements.

	Epoch	∆ρ (O-C) ∆θ (O-C) Observer
		( ′′ )	( • )
	2001.357	0.108	-0.9 WSI
	2002.386	0.059	-0.4 WSI
	2002.496	0.017	-0.5 Dal
	2003.309	0.073	0.2 WSI
	2004.365	-0.006	0.9 WSI
	2005.460	-0.035	-0.4 WSI
	2006.328	0.010	0.3 WSI
	2007.440	0.031	-0.5 WSI
	2008.398	0.045	-0.5 WSI
	2009.521	0.046	-0.0 WSI
	2009.593	0.032 P	-0.3 P Sca
	Table 6 ADS 11484: O-C residuals of our new orbit (af-
	ter 1998.0). The symbol P indicates PISCO measurements.
	Epoch	∆ρ (O-C) ∆θ (O-C) Observer
		( ′′ )	( • )
	1999.504	0.063	-4.9 Pri
	1999.504	0.063	-4.3 Lin
	2000.570	-0.017	-6.4 Alz
	2001.520	-0.038	-4.9 Alz
	2001.690	0.002	-0.4 WSI
	2002.550	-0.028	0.6 Alz
	2006.564	0.002	0.6 Hrt
	2007.600	-0.007	-1.1 Alz
	2009.670	0.010 P	5.6 P Sca

Table 7

 7 MLR 198: O-C residuals of our new orbit (after 1986.0). The symbol P indicates PISCO measurements.

	Epoch	∆ρ (O-C) ∆θ (O-C) Observer
				( ′′ )		( • )
	1987.267		-0.007		-0.4 Hrt
	1987.510		0.026		8.9 Mlr
	1988.443		0.004		-6.7 Cou
	1989.228		-0.002		-0.0 McA
	1990.263		0.002		0.2 Hrt
	1991.328		0.011		-0.2 Hrt
	1993.198		0.027		0.1 Hrt
	2007.607		-0.035		-1.8 Msn
	2008.461		-0.038		1.7 Msn
	2009.637		-0.026 P		0.9 P Sca
	Table 8 New ephemerides of ADS 8035, 9982, 11484 and
	MLR 198.
	ADS 8035 ADS 9982 ADS 11484 MLR 198
	Epoch	ρ	θ	ρ	θ	ρ	θ	ρ	θ
		( ′′ )	( • )	( ′′ ) ( • ) ( ′′ )	( • )	( ′′ ) ( • )
	2010.0 0.582 21.0 3.418 17.9 0.376 76.7 0.247 68.3
	2011.0 0.619 14.4 3.435 17.8 0.375 75.8 0.253 65.8
	2012.0 0.653 8.5 3.451 17.6 0.374 74.9 0.258 63.3
	2013.0 0.683 3.2 3.467 17.5 0.373 74.0 0.263 61.0
	2014.0 0.710 358.3 3.483 17.3 0.372 73.1 0.268 58.7
	2015.0 0.734 353.7 3.499 17.2 0.372 72.2 0.272 56.5
	2016.0 0.754 349.4 3.514 17.0 0.370 71.3 0.276 54.4
	2017.0 0.772 345.3 3.530 16.9 0.369 70.4 0.279 52.3
	2018.0 0.786 341.4 3.545 16.7 0.368 69.5 0.282 50.3
	2019.0 0.798 337.6 3.560 16.6 0.367 68.6 0.284 48.2
	2020.0 0.807 334.0 3.575 16.4 0.366 67.7 0.286 46.3
	2021.0 0.813 330.3 3.589 16.3 0.364 66.8 0.287 44.3
	4.2 New orbit of ADS 9982, STF 2026

Table 9

 9 Physical parameters (̟ dyn , a and M total ) derived from the new orbital elements.

	Name	HIP	mV	Spectral type	̟ dyn	̟HIP	a		M total	Source of ̟HIP
					(mas ) (mas )	( ′′ ) (AU)	(M⊙)
	ADS 8035	54061 1.79 K0Iab + F0V	24.0	26.38	0.590	22.4	5.7	ESA (1997)
					±4	±0.53 ±0.026	±1.1	±0.8
	"	"	"	K0III + F0V	33.8	26.54	0.590	22.2	5.6 van Leeuwen (2007)
					±4	±0.48 ±0.026	±1.1	±0.8
	ADS 9982	79702 8.74	K4V	39.5	38.84	2.380	61.3	1.2	ESA (1997)
					±4	±2.96 ±0.042	±4.7	±0.3
	"	"	"	"		38.46	2.380	61.9	1.2 van Leeuwen (2007)
						±1.95 ±0.042	±3.1	±0.2
	ADS 11484 91167 7.66	A2	5.6	5.59	0.511	91.4	4.5	ESA (1997)
					±2	±1.94		±32	±4.7
	"	"	"	"		4.49	0.511	114	8.7 van Leeuwen (2007)
						±1.04		±26	±6.1
	MLR 198	81757	6.8	A2	8.3	8.26	0.195	23.6	4.4	ESA (1997)
					±2	±0.59 ±0.065	±8.1	±4.6
	"	"	"	"		9.27	0.195	21.0	3.1 van Leeuwen (2007)
						±0.41 ±0.065	±7.1	±3.2
	ment with Hipparcos parallax (both with ESA, 1997
	and with van Leeuwen, 2007).

www.an-journal.org

Acknowledgements. We thank the members of the United States Naval Observatory, Washington DC, for kindly sending on request some lists of measurements of visual binaries. We also thank W.I. Hartkopf for his useful report on this paper. This work has made use of the "Fourth Catalogue of Interferometric Measurements of Binary Stars" (http://ad.usno. navy.mil/wds/int4), the "Sixth Catalogue of Orbits of Visual Binary Stars" (http://ad.usno.navy.mil/wds/orb6), and the Washington Double Star Catalogue (http://ad.usno.navy.mil/wds/wds) maintained at the U.S. Naval Observatory, and the SIMBAD astronomical data base (http://simbad.u-strasbg.fr/simbad) operated by the Centre de Données Astronomiques de Strasbourg (France).