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The purpose of this study is to build and manage environment models with line segments from sonar range data on obstacles in unknown and varied environments. The proposed method therefore employs a two-stage data-transform process in order to extract environmental line segments from range data on obstacles. In the first stage, the occupancy grid extracted from the range data is accumulated to form a two-dimensional local histogram grid. In the second stage, a line histogram extracted from a local histogram grid is based on a Hough transform, and matching serves asa means of comparing each of the segments on a global line segments map against the line segments to detect the degree of similarity inthe overlap, orientation, and arrangement. Each of these tests is formulated by comparing one of the parameters in the segment representation. After the tests, new line segments can be found at maximum-density cells in the line histogram, and they are composed onto the global line segment map. The proposed technique is demonstrated in experiments in an indoor environment.

To determine the influence of qualification on field and currency, the model is presented that there is the connection between job competence and job fit about the function of qualification. To find out this connection, the study is being done and based on this, a clue of qualification on field and currency is tried to figure out. First, in case of national technical qualification holders in Machinery field, the type of the function of qualification(signal, guide, screen functions) of job competence and job fit shows correlation between them. Second, the job competence and job fit of the owner of national technical qualification in Machinery field is mostly affected by signal function. Thirdly, the mediating effect of job competence on the effect of the function of qualification on job-fit is showed by the types of function of qualification. Guide function does not have any mediation effect, but signal function and screen function have the mediation effect. Especially, out of all, signal function is the most affecting factor of mediating effect. Lastly, the model of the relationship between subordinate factors by types of function of qualification on job competence and job fitis presented.

New film forming aromatic poly(amide-imide)s containing isoindoloquinazolinedione (IQ) unit in the backbone chain (polymerXIV) have been successfully synthesized by preparing prepolymers of poly(amic acid-carbonamide), followed by subsequent thermal cyclization of the prepolymers. 4,4′-Diamino-3′-carbamoylbenzanilide (DACB)V has been synthesized by reduction of 3′-carbamoyl-4′-amino-4-nitrobenzanilideIV. The prepolymers of poly(amic-acid-carbonamide) (polymersVII andVIII) which exhibit viscosities ranging from 1.4 to 1.7 dl/g have been prepared by a condensation polymerization of monomers such as BPDA, ODA, and DACB. PolymerXIV has been obtained by thermal cyclization of the polymersVII andVIII. During the thermal cyclization reaction, imide ring structure was first introduced and then transformed to the structure of IQ unit. The thermal degradation rate of the resultant polymers were influenced by the cleavage of amide bond but the final char yield was comparable to that of poly(BPDA-ODA).

A new aromatic polyamide containing a pendant ethoxycarbonyl group was successfully synthesized from the reaction between 4,4'-diamino-2'-ethoxycarbonyl-benzanilide and terephthaloyl chloride. The new polymer was soluble in organic solvents such as N-methyl-2-pyrrolidone and dimethylacetamide, and a tough and transparent film was cast from the polymer solution with viscosities ranging from 2.6 to 5.6 dL/g. When the polymer film was heat-treated at a temperature greater than 300 °C, a cyclization reaction occurred between the ethoxycarbonyl group and the adjacent amide bond to form a benzoxazinone unit in the polymer backbone. The thermal decomposition onset temperature of the cyclized film was about 523 °C, which was somewhat lower than that of poly(p-phenylene terephthalamide) (PPTA; 566 C); however, the decomposition rate was slower than that of PPTA to yield a higher char residue. The dispersion temperature of the uncyclized poly(4,4'-diamino-2'-ethoxycarbonylbenzanilide terephthalamide) (PDEBTA) was about 340 °C, whereas that of the cyclized PDEBTA was not clear.

To prepare thermally stable and high-performance polymeric films, new solvent-soluble aromatic polyamides with a carbamoyl pendant group, namely poly(4,4'-diamino-3'-carbamoylbenzanilide terephthalamide) (p-PDCBTA) and poly(4,4'-diamino-3'-carbamoylbenzanilide isophthalamide) (m-PDCBTA), were synthesized. The polymers were cyclized at around 200 to 350 °C to form quinazolone and benzoxazinone units along the polymer backbone. The decomposition onset temperatures of the cyclized m- and p-PDCBTAs were 457 and 524 °C, respectively, lower than that of poly(p-phenylene terephthalamide) (566 °C For the p-PDCBTA film drawn by 40% and heat-treated, the tensile strength and Young's modulus were 421 MPa and 16.4 GPa, respectively. The film cyclized at 350 °C showed a storage modulus (E') of 1 × 10 11 dyne/cm 2 (10 GPa) over the temperature range of room temperature to 400 °C.

A new thermally stable, high strength and high modulus aromatic polyamide film was obtained via the formation of the molecular composite of p-PDCBTA and P-LCl. The two polymers exhibited good miscibility identified with the measurement of dynamic mechanical property and FTIR spectra. By the combination of drawing by 40% and subsequent heat treatment, the tensile property of the composite film could be achieved to the strength of 450 MPa and the modulus of 24 GPa, which were sustainable upto 400 °C.

In order to study systematically the effect of halogen substituents on both the solubility and the thermal stability of aromatic polyamides, new diamine monomers have been synthesized by introducing chlorine groups onto various positions of 4,4'-diaminobenzanilide for the preparation of chlorinated aromatic polyamides. The monochlorinated aromatic polyamides, i.e., P-LCl and P-RCl, exhibited liquid crystalline property in 100% sulfuric acid solution in the temperature range from 40 and 60°C. However, the dichlorinated sample, i.e. P-LRCl, did not exhibit the liquid crystalline property due to the bulkiness of two chlorine groups. Both P-LCl and P-RCl exhibited unimodal decomposition behavior in contrast to the chlorinated poly(p-phenylene terephthalamide) (PPTA) that has been known to show bimodal decomposition behavior. The decomposition onset temperature of both P-LCl and P-RCl was 567°C, which was higher than 549°C of unchlorinated polyamide, P-NCl, but the same as that of PPTA. The char yield was about 50% for both P-LCl and P-RCl and higher than 40% of both PPTA and P-NCl. In the case of P-LRCl, the decomposition onset temperature was 480°C, but the highest char yield of 60% was obtained.

This paper presents a position sensorless control scheme for synchronous reluctance motors using high frequency current injection. The rotor has inherent rotor saliency and its angle is estimated from d and q stator current injection and the appropriate signal demodulation. This scheme gives robust and dynamic estimation of the rotor angle independent of the operating condition including standstill and light and heavy loading. Experimental results of closed loop speed control of a 3.75 kW axially laminated synchronous reluctance motor are given to verify the proposed scheme.

This paper presents a position sensorless control scheme of a synchronous reluctance motor (SynRM) combining a high-frequency current injection method in the low-speed region and the flux estimation method based on the stator voltages in the high-speed region. The rotor has inherent saliency, and its angle can be estimated from d-axis stator current injection and the appropriate signal demodulation in a low-speed region. In the high-speed region, the rotor can be estimated by the stator flux from the voltage information. The scheme gives a robust and dynamic estimation of the rotor angle, independent of the operating conditions, including speed and load conditions. Experimental results of closed-loop speed and position control with a 3.75 kW axially laminated SynRM are given to verify the proposed scheme.

In this paper, a nonlinear controller capable of high dynamic torque regulation and efficiency optimization of the synchronous reluctance motor (SynRM) using input-output feedback linearization is proposed. The cross-coupling effects in the SynRM model and the torque nonlinearity due to the iron losses in torque-speed characteristics of the SynRM are discussed. The criterion for the efficiency optimization is also introduced and investigated. Since the proposed nonlinear controller directly regulates the torque by selecting the product of d- and q-axes torque currents as one of the output variables, the nonlinear and cross-coupling aspects between the d-and q-axes torque currents and the terminal currents can he eliminated. Hence, the linear torque-speed characteristic can be achieved. In addition, by controlling the power loss-minimizing criterion directly, the proposed controller can optimize the efficiency of the SynRM without deteriorating the dynamics performance.

In this paper a method of the torque control attenuating the undesired torque pulsation for brushless DC motor with nonideal trapezoidal back EMF is presented. It is the direct torque control method in which the applied output voltage is calculated from the reference torque and the torque of the previous step in the two-phase conducting period and in the commutation period considering the back EMF waveform. The time delay due to the calculation is compensated by the one step ahead current prediction. To measure the instantaneous torque ripple, a torque observer is constructed using a high precision encoder of 50000 pulse per revolution. The simulation and experimental results show that the proposed method reduces the torque ripple significantly and that it keeps the torque control dynamics as well. >

The authors present an analytical study of the torque ripple due to the phase commutation in a BLDCM (brushless DC motor) fed by HCRPWM-VSI (hysteresis current regulated pulse width modulation voltage source inverter). In order to show the duration of the phase commutation and the torque ripple during the phase commutation, the instantaneous trapezoidal waveform of the back EMF and the amplitude of the phase current are considered. Simulation and experimental results indicate that the duration of the phase commutation and the current ripple during the phase commutation vary with speed and depend on the amplitude of the phase current. Also, the effect on the motor speed due to the torque ripple during the phase commutation is studied. >

In this paper, a new type of gearless traction machine drive system with a permanent-magnet (PM) motor for high speed elevators is presented. This application of a PM motor to the elevator traction machine enables several improvements including higher efficiency, greater ride comfort, and miniaturization and so on. A voltage-fed 3-phase PWM rectifier is also adopted so that DC bus voltage regulation, bi-directional power flow and controllable power factor with reduced input current harmonics are possible. To guarantee reliability of the whole system, the RC terminator at the motor side is designed for decreasing d/spl nu//dt ratio at motor terminal and then preventing insulation failure of the motor. Some experimental results of 240 m/min operation are given to verify the effectiveness of the proposed scheme.

This paper describes the two control techniques to perform the sensorless vector control of interior permanent magnet synchronous motors (IPMSM) by injecting the high frequency voltage to the stator terminal. The first technique is the estimation algorithm of the rotor initial position including the identification of the rotor magnet N-S polarity at standstill. IPMSM possess the saliency which produces the ellipse of the stator current when the high frequency voltage is injected to the motor terminal. The major axis angle of the current ellipse gives rotor position information at standstill. The center of the current ellipse shifts because of the magnetic saturation effect from the origin, which makes it possible to identify the rotor magnet N-S polarity. The averaging method of the multi-cycles stator current is utilized to identify the rotor magnet N-S polarity. This averaging method increases the accuracy of the position estimation and solves the current ripple problem. The second control technique is a sensorless control algorithm that injects the high frequency current to the stator terminal in order to estimate the rotor position and speed. The rotor position and speed for sensorless vector control is achieved by appropriate signal processing to extract the position information from the stator current even in the low speed range. Experimental results are presented to verify the feasibility of the proposed control schemes.

This paper presents a direct torque controller of a synchronous reluctance motor based on the stator current vector. The stator direct and quadrature voltages which can generate the desired torque are directly calculated from the machine model. A simple model without the core loss and a modified model which includes the core loss are considered in the proposed method. The results show that the fast and highly dynamic torque response can be obtained by the proposed method. The simulation and experimental results are presented to show the validity of the proposed method using the test synchronous reluctance motor.

In this paper, efficiency maximized current angle condition in synchronous reluctance motor (SynRM) which minimizes the copper and iron losses is derived based on the equivalent circuit model of the machine. The constraint in obtaining the optimal angle is constant output torque for given operating speed. The efficiency of the motor can be improved by the proposed method especially in the light load condition. For SynRM, torque dynamics can be maintained even with controlling the flux level because the generated torque is directly proportional to the stator current. This is not the case of induction motor since the rotor flux linkage is built up with the rotor time constant. In the proposed algorithm simple iron loss compensation routine is added to compensate the torque nonlinearity due to the iron loss. The proposed algorithm allows the electromagnetic losses in variable speed and torque drives to be reduced while keeping good torque control dynamics. Simulation and experimental results are presented to show the validity of the proposed algorithm.

Many heterocyclic polymers have been recently reported as thermally stable polymers. Polymer containing the benzoxazinone unit in the main chain known to have remarkable thennal stability is one of them. Polybenzoxazinones1,2 are capable of being prepared by the reaction of suitable aromatic diaminodicarboxylic acids with aromatic dicarboxylic acid halides in polyphosphoric acid at high tempera tare or in dimethyl acetamide(DMAc) at low temperature. Our interest in polyamides having pendant ethoxycarbonyl groups has led to the synthesis of aromatic poly (4,4′-diamino-6-ethoxycarbonyl benzanilido terephthalamide) (PDEBTA) by solution polymerization of 4,4′-diamino-6-ethoxycarbonyl benzanilide with terephthaloyl chloride. The mechanism of cyclization of aromatic PDEBTA will be described on the basis of a model compound reaction and the physical properties of uncyclized PDEBTA are also to be discussed.

Difference of the mechanical properties between calender films and melt spun fibers, produced by using low molecular weight polyethylene, was discussed in terms of morphological aspects. The viscosity-average molecular weights of the calender films and the melt spun fibers were 70,000 and 54,000, respectively. The orientation factor of the c-axis of the film with a maximum draw ratio of 14 was 0.9291, indicating a high orientational degree of the c-axis with respect to the machine direction. This value is slightly higher than that of the drawn fiber (0.8423). In contrast, the Young’s modulus of the drawn film was only 15.3 GPa, while the Young’s modulus of the drawn fiber reached 55.6 GPa. The results were explained by the difference of the morphological properties which were obtained by using small angle X-ray scattering, wide angle X-ray diffraction, small angle light scattering, and birefringence measurements. A conclusion drawn from this work is as follows; the preferential orientation of the c-axes of the films is mainly due to the rotation of crystallites, while that for the fibers is due to the crystal transformation from a folded to a fibrous type.