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With more and more applications of high-power PMSM in low-speed applications, the accuracy of the control system has also become more demanding. It is difficult to detect the position and control the speed of the motor according to the counter EMF because its amplitude is small. This paper adopts an improved high frequency signal injection method and the filtering method of single synchronous shafting filter and PLL, a set of high-power sensorless AC speed regulating system is designed based on the NPC three-level back-to-back converter with IGBTs which improves the robustness and control accuracy of low-speed high-power PMSM. The experimental and simulation results show that the control system meets the design requirements of engineering application.

In this study, a fluorescent reagent, 4-((aminooxy)methyl)-7-hydroxycoumarin (AOHC), was for the first time applied to label the low-molecular-mass aldehydes (LMMAs) through reductive oxyamination reaction to afford single N,O-substituted oxyamine derivatives at room temperatures with derivatization efficiencies as high as 96.8%. In the following high-performance liquid chromatography with fluorescence detection analysis, 12 LMMAs, including furfurals, aromatic aldehydes, and aliphatic aldehydes, were baseline-separated on an ODS column and detected with low limits of detection (LODs) (0.2-50 nM), and good precisions (intraday relative standard deviations [RSDs] were 2.40-4.68%, and interday RSDs were 4.65-8.91%). This approach was then adopted to analyze six alcoholic beverages and five dairy products, and nine LMMAs with concentrations in the 0.28-798.16 μM range were successfully detected with excellent accuracies (recoveries were 92.2-106.2%). Finally, the results were statistically analyzed and discussed. The proposed method has several advantages, including high sensitivity, room-temperature labeling, and the avoidance of further extraction and/or enrichment procedures, demonstrating its great utility for monitoring LMMAs in various complex matrices.

For permanent magnet synchronous motor speed and rotor position easily affected by the mechanical sensor signal transmission precision, to improve the performance of permanent magnet synchronous motor drive, the speed control system satisfies the requirement of fast response, and the complicated condition of frequent load disturbance has stronger resistance, this paper designed a small nerve network optimization of permanent magnet synchronous motor intelligent control system. The intelligent control system will be small neural networks applied to the model reference adaptive control of permanent magnet synchronous motor speed control system. On this basis, the structures, permanent magnet synchronous motor control system simulation, the simulation results show the system can accurately measure the rotational speed, rotor position and compared with the traditional model reference adaptive control, motor start-up speed no overshoot, has the stronger ability to resist load disturbance and load disturbance after speed restore faster (6 ms), in the motor control has strong practical application value.

A high - precision and high - performance converter control system is developed in this paper. It is a combination of Multi-CPU and DSP based on VME bus and integrates various data communication technologies. The digital control system has been successfully run on the high-power IGCT five-level converter and drive a 20MW synchronous motor. The control system can realize high-speed communication between two CPU boards through reflected memory, data communication between five-level converter and water cooling system, input high-voltage switch cabinet, output high-voltage switch cabinet and other external auxiliary electrical equipment through Profibus-DP, and data communication between the control system and the higher level control system can also be realized through Ethernet. The control system can not only realize high performance and high precision motor control, but also has the advantages of intelligent, integrated and networked.

The input-series-output-parallel (ISOP) DC-DC converter with SiC-MOSFETs is researched in this paper. This converter is consisted of multiple dual active bridges (DABs). Each DAB adopts symmetrical CLLC resonant circuit topology including high-frequency transformer. The application of SiC-MOSFETs improves the switching frequency and performance of the converter greatly and it can be applied to medium and high voltage DC distribution grid. A simplified open-loop square-wave modulation strategy is introduced and simulation result is shown. Before the normal working of isolated DAB, the output side capacitor should be pre-charged to prevent overcurrent and voltage oscillation. In this paper one pre-charge method is proposed. The simulations shows that the output dc voltage rises gradually to the rated voltage.

The traditional PLL(Phase Locked Loop) algorithm cannot meet the requirement of fast and accurate phase locking in the case of unbalanced three-phase voltage in power grid. On the basis of analyzing the traditional PLL, this paper proposes a fast PLL strategy based on the new filtering method. The traditional method uses all-pass filter, whose parameters cannot be easily adjusted. When the network parameters change, the detection accuracy and real-time performance of the network voltage are greatly reduced. The new phase locking strategy adopts FIR (Finite Impulse Response), which can effectively overcome the influence of power network parameters’ change on PLL performance. The simulation results verify that the new fast phase-locking strategy of the grid voltage can meet the engineering application requirements within 5ms under the fault of unbalanced three-phase voltage and other complex working conditions including harmonic and phase shift.

This paper investigates the switching characteristics of SiC MOSFET. The turn-on and turn-off switching transient processes of power device are analyzed respectively by the mathematical equation on the basis of double-pulse test circuit. Based on the analysis of the influence of parasitic parameters on the switching characteristics, it indicates that the appropriate driving resistance should be selected and power circuit stray inductance should be reduced. The prototype of dual active bridge (DAB) has been built and the experimental results validate the correctness of theoretical analysis.

This paper presents a speed identification method based on the model reference adaptive system (MRAS) of Permanent Magnet Synchronous Motor (PMSM). A stator flux observer based on a new voltage model is designed, using the compensation algorithm for the orthogonality of stator flux and back EMF. This paper designs an improved MRAS model based on this new voltage model and it takes the flux linkage as the state variable in the $\alpha\beta 0$ coordinate system. A sensorless vector control system for PMSM is constructed. Simulation results of the drive performance in MATLAB/Simulink are presented. Finally, this method has been applied to the high-power application, combined with a three-level inverter. The experiment has been carried out with DSP28335 as the core of the control circuit of the platform. Results indicate the correctness of the theoretical analysis.

Emotions affect cognition, perception, and response to the external world. In this study, six open spaces on a university campus in Xi'an, China were selected to detect emotional responses to thermal perceptions from 516 staff and students. Respondents' emotional changes and subjective thermal sensation vote (TSV) were recorded as they completed a stressful task. Responses were rated using a Positive and Negative Affect Schedule (PANAS) and thermal comfort questionnaires. Respondents' subjective thermal sensation changes, emotional responses, and influence factors on thermal sensation under different physiological equivalent temperature (PET) ranges were analyzed. Results showed that: (1) As air temperature (Ta), globe temperature (Tg) and mean radiation temperature (Tmrt) increased, positive affect (PA) varied as an inverted V-shaped trend, but negative affect (NA) showed the opposite trend. Sky view factors were negatively related to PA, and positively related to NA in summer. Visible green index was negatively related to PA in winter. (2) Neutral PET, neutral PET ranges, preferred PET and thermal acceptable ranges were 19.4 °C, 12.2–26.6 °C, 25.2 °C and 12.9–33.9 °C before a stressful task, 16.3 °C, 8.1–24.5 °C, 24.3 °C and 11.2–33.5 °C after the stressful task, and 20.0 °C, 12.7–27.3 °C, 25.3 °C and 14.1–36.3 °C after recovery, respectively. (3) Wind speed (Va) and Tmrt were the primary meteorological parameters that influenced respondents' thermal sensation. TSV approached to neutral as PA increased; increasing NA may increase TSV. Additionally, the influence of emotional regulation on TSV varied as the range of PET changed.

The influence of emulsified oil, suspended solids, Fe3+, Fe2+, cationic water clarifier and sulfate-reducing (SR) bacteria on the aggregation behavior of residual hydrophobic modified polyacrylamide in treated oily wastewater from polymer flooding was studied by fluorescence spectroscopy and dynamic light scattering. The result of I 1 /I 3 showed that the polarity of hydrophobic microdomains increased, whereas the size of the hydrophobic microdomains may be decreased, where the value of I 1 /I 3 represents the ratio of the intensity of peak I 1 (374.0 nm) to that of peak I 3 (385.0 nm) of the vibration fine structure of pyrene monomer emission in residual polymer solution. The results of the ratio of I 1 at 48 h to I 1 at 0 h (I 1,48h /I 1,0h) indicated that oil and cationic water clarifier could inhibit the aggregation to some extent, while Fe2+ and suspended solids were helpful for aggregation, and Fe3+ and SR bacteria had no significant influence on the aggregation of polymer.

As a function of temperature in aqueous solutions, the adsorption and aggregation of N,N’-bis (tetradecyl dimethyl)-1,2-dibromide-ethanediyl ammonium salt (GS14-2-14) and N,N’-bis (hexadecyl dimethyl)-1,2-dibromide-ethanediyl ammonium salt (GS16-2-16), were researched with drop-volume technique and conductometry, respectively. The results of surface tension measurements, which were analyzed by originally developed thermodynamic equations, illustrate that GS14-2-14 has a better surface activity and arranges more tightly in the adsorbed film than GS16-2-16. The data of conductivity were used to find critical micelle concentration (cmc) and counterion binding degree of micelle (β). Thermodynamic parameters of micellization were also obtained from the temperature dependence of cmc values. From the study, it is discovered that the micellization process is spontaneous and exothermic in nature and it is mainly driven by entropy.

The effects of ferrous ion (Fe2+) on the aggregation of residual hydrophobic-modified polyacrylamide APP4 were studied by fluorescence spectrum and dynamic light scattering (DLS). The result showed that Fe2+ was helpful for aggregation degree of APP4, which is not good for the stability of APP4 in water. Therefore, ethylenediaminetetraacetic disodium salt (EDTA) and sodium citrate were used to eliminate this influence. Several experiment results presented that EDTA can effectively eliminate the influence of Fe2+ on the residual APP4 when its concentration was 50 mg/L.

The influences of Fe2+ on the aggregation behavior of residual hydrophobic modified polyacryamide (HMPAM) in treated oily wastewater were studied by fluorescence spectrum and DLS. The result of I1/I3 showed that the polarity of hydrophobic domain increased and the size of hydrophobic domain may be decreased with the increasing of Fe2+ in produced water. Fe2+ was helpful for the increase of hydrophobic domain, therefore due to the aggregation degree for HMPAM.

Multidrug resistance (MDR) is a major cause for incurable breast cancer. Salvianolic acid A (SAA), the hydrophilic polyphenolic derivative of Salvia miltiorrhiza Bunge (Danshen/Red Sage), was examined for cytotoxicities to MDR MCF-7 human breast cancer cells and their parental counterparts. We have shown that SAA inhibited proliferation, caused cell cycle arrest at the S phase, and induced apoptosis dose dependently to the two kinds of cancer cells. However, the resistant cells were significantly susceptible to the inhibition of SAA compared with the parental cells. SAA increased the level of reactive oxygen species (ROS) by 6.2-fold in the resistant cells, whereas the level of SAA-induced ROS changed only by 1.6-fold in their parental counterparts. Thus, the data showed that the selective cytotoxicity resulted from the hypersensitivity of the resistant cells to the strongly elevated ROS by SAA. In addition, SAA-triggered apoptosis was associated with increased caspase-3 activity, disrupted mitochondrial membrane potential, downregulated Bcl-2 expression, and upregulated Bax expression in the resistant cells. Moreover, SAA downregulated the level of P-glycoprotein, which was overexpressed in the resistant cells. This indicated that SAA modulated MDR. Furthermore, SAA showed higher antitumor activity than did doxorubicin in xenografts established from the resistant cells. The present work raised a possibility that SAA might be considered a potential choice to overcome MDR for the selective susceptibility of the resistant breast cancer cells to SAA treatment.

It is difficult to address the problem of occlusion and loss of target when a single image tracking algorithm is utilized in high reliability occasions, such as prison, coal mines and military area. This paper presents a novel tracking and monitoring system based on wireless location and video. A coordinate frame of wireless system of scene constructed by binding the targets with RSSI labels is used to extract the real-time location information of targets. A high-speed ball camera is used to set up the coordinate frame based on vision system. Double shaft angle encoder added on the high-speed ball camera and control system devised based on ARM are adopted to obtain real-time coordinates of field of visual system. Thus, it solves the problems of the high-speed ball camera without real-time angle feedback, and improves the reliability of the system. It makes the position of camera as the origin of coordinates, and fuses the two coordinates to find out the relationship with Pan & Tilt and the label position. Firstly, the system detects and captures targets by the help of label. Secondly, using the image processing algorithm tracks the targets on a larger scale. Finally, it uses the label information as a feedback to correct position when the targets lost or be covered. Results show that, the new system is robust in the large-scale scene and complicated background.

Conformance control using preformed gels (PGs) is an effective method to reduce water cut in production oilwells. However, PGs are unable to thicken formation of water, and the improvement of water-oil mobility is limited. Compared with PGs, hydrolysable PGs (HPGs) with labile crosslinker incorporated could thicken the brine gradually. In this study, a series of HPGs were prepared based on labile crosslinker poly(ethylene glycol) diacrylate, self-crosslinker N,N-dimethylacrylamide (DMAM), and nanomaterial laponite. The long-term thermal stability, swelling property, and thickening power of the HPGs were successively examined. It was demonstrated that DMAM remarkably improved the long-term thermal stability of HPGs, and also imparted the swelling and thickening properties during aging period, while laponite effectively increased the viscosity of HPGs suspension but weakened the swelling ratio. Degradation monitored by nuclear magnetic resonance spectroscopy indicated that HPGs are decrosslinked gradually through the hydrolysis of labile crosslinker and then release a terpolymer of acrylamide, acrylate, and DMAM. The hybrid fluid containing the terpolymer and nanomaterial resulted in the increased viscosity of HPGs suspension. Artificial core flooding results showed that HPGs have good sealing capacity for conformance control, and incremental oil was recovered by using HPGs against traditional PGs with similar plugging efficiency owing to the increased viscosity of the HPGs dispersion. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45413.

In order to reduce the high accident rate in the construction industry, it is necessary to raise safety knowledge level of management staffs and workers. This paper attempts to use the network analysis method and build a Safety Knowledge Sharing Network among different persons from the owner, designer, contractor, and supervision firm. The relationships among different persons, safety knowledge structure, and knowledge transferring routines will be identified. The network can be used to evaluate the safety knowledge sharing status of real projects, find defects, and search for improvement measurements. The exploration and related results can be adopted to improve safety education and training, so as to promote safety management in the whole construction industry.

hypothesized that aMCI patients would show attenuated functional connectivity in medial parietal and temporal cortex compared to age-matched controls. We also hypothesized that functional connectivity in midline cortical regions important for self-appraisal would inversely correlate with level of anosognosia. Methods: Sixteen MCI patients and sixteen age and education control participants were included in the analysis. The vPCC region showing activity to self-appraisal in a sample of 203 cognitively healthy adults was used as the seed region for the analysis; correlation maps were generated guided by published procedures. Results: Our analysis of group differences in functional connectivity revealed that MCI participants show attenuated connectivity in the PCC and a ventromedial prefrontal region (Figure 1). We also examined the relationship between functional connectivity and level of cognitive anosognosia in the MCI group. Results revealed a significant inverse relationship between level of cognitive anosognosia and functional connectivity in the ventromedial prefrontal cortex and bilateral hippocampi (Figure 2). Conclusions: This finding highlights the level of anosognosia in MCI as an important predictor of functional connectivity in brain regions important for self-appraisal that are vulnerable to changes associated with early AD.

This paper provides a systematic approach for copying and pasting of freeform features among existing models of design. Freeform feature as complex high-level shape entity enables a fast creation and modification of a geometric model in the context of both mechanical and aesthetic design. Copying and pasting of freeform feature can enhance not only the rapid shaping of the geometric model itself, but also the inheriting of design knowledge built in existing designs. In this paper definitions of freeform feature are reviewed and consummated. An analysis of parametric and topological relevancy of freeform feature is given in terms of copying operation and an elaboration of the reconstruction of freeform feature in a new geometric model regarding to pasting operation is presented. The reuse of freeform feature is discussed, and related algorithms are presented in detail.Copyright © 2002 by ASME