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Effects of a structurally related substance on the crystallization of paracetamol

Ali SALEEMI, I.I. ONYEMELUKWE, Zoltan NAGY

《化学科学与工程前沿(英文)》 2013年 第7卷 第1期   页码 79-87 doi: 10.1007/s11705-013-1308-7

摘要: Paracetamol (PCM) was crystallized from an isopropanol (IPA) solution containing various small amounts of metacetamol as an additive. The effect on the nucleation kinetics was studied by measuring the induction time to nucleation and the metastable zone width using focused beam reflectance measurements (FBRM) and attenuated total reflectance (ATR-UV/Vis) spectroscopy. Both the induction time and the metastable zone width were expressed as functions of the additive concentration. Small amounts of metacetamol (1–4 mol-%) were found to cause significant inhibition to the nucleation by extending both the induction time and the metastable zone width. A progressive change in the morphology of the paracetamol crystals from tabular to columnar habit was observed with increasing metacetamol concentration. The solvent also had a significant effect on the size of the paracetamol crystals as smaller crystals were obtained in IPA than in aqueous solution. The dissolution rate of paracetamol was improved by the incorporation of metacetamol with 4 mol-% having the most effect. A supersaturation control (SSC) approach was implemented for the PCM-IPA system with and without metacetamol in an attempt to control and obtain larger metacetamol-doped paracetamol crystals.

关键词: acetaminophen     metacetamol     crystallization     metastable zone width     induction time     supersaturation control    

Constant temperature control of tundish induction heating power supply for metallurgical manufacturing

Yufei YUE, Qianming XU, Peng GUO, An LUO

《能源前沿(英文)》 2019年 第13卷 第1期   页码 16-26 doi: 10.1007/s11708-018-0572-0

摘要: The tundish induction heating power supply (TIHPS) is one of the most important equipment in the continuous casting process for metallurgical manufacturing. Specially, the constant temperature control is greatly significant for metallurgical manufacturing. In terms of the relationship between TIH load temperature and output power of TIHPS, the constant temperature control can be realized by power control. In this paper, a TIHPS structure with three-phase PWM rectifiers and full-bridge cascaded inverter is proposed. Besides, an input harmonic current blocking strategy and a load voltage feedforward control are also proposed to realize constant temperature control. To meet the requirement of the system, controller parameters are designed properly. Experiments are conducted to validate the feasibility and effectiveness of the proposed TIHPS topology and the control methods.

关键词: tundish induction heating power supply (TIHPS)     constant temperature control     input harmonic current blocking     load voltage feedforward    

Nucleation and growth mechanism of cefodizime sodium at different solvent compositions

Xinwei ZHANG, Shudong ZHANG, Xiaodan SUN, Zequn YIN, Quanjie LIU, Xiwen ZHANG, Qiuxiang YIN

《化学科学与工程前沿(英文)》 2013年 第7卷 第4期   页码 490-495 doi: 10.1007/s11705-013-1350-5

摘要: The induction time of cefodizime sodium was measured in ethanol-water at different solvent compositions by the laser technology measurement. The results indicate that the solvent composition played an important role in the supersaturation and the nucleation process of cefodizime sodium solution. According to the modified classical nucleation theory, the nucleation and growth mechanism were identified. The correlation results show that heterogeneous nucleation dominated the nucleation process at lower supersaturation, where homogeneous nucleation is the most important mechanism at higher supersaturation. Based on the correlated results, the 2D mediated growth mechanism had the highest correlation coefficients ( ), so this mechanism was selected as the proper growth mechanism for cefodizime sodium.

关键词: cefodizime sodium     induction time     primary nucleation     growth mechanism    

Brown and beige fat: the metabolic function, induction, and therapeutic potential

null

《医学前沿(英文)》 2015年 第9卷 第2期   页码 162-172 doi: 10.1007/s11684-015-0382-2

摘要:

Adipose tissue is an important organ for energy homeostasis. White adipose tissue stores energy in the form of triglycerides, whereas brown adipocytes and recently identified beige adipocytes are specialized in dissipating energy by thermogenesis or contribution to dispose glucose and clear triglycerides in blood. The inverse correlation between the brown adipose tissue activity and body mass suggests its protective role against body fat accumulation. Thus, recruitment and activation of brown or beige adipose tissue become particularly appealing targets for increasing energy expenditure. Angiogenesis and sympathetic nerve signals are the fundamental determinants for brown and beige adipose tissue development, as well as for their metabolic functions. Secretary factors including BMPs can induce the development, the activation of brown or beige adipose tissue, which seem to be promising for therapeutic development.

关键词: brown adipocyte     beige adipocyte     metabolism     obesity    

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

《能源前沿(英文)》 2015年 第9卷 第4期   页码 472-485 doi: 10.1007/s11708-015-0373-7

摘要: It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors (IMs) are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.

关键词: isolated hybrid power system (IHPS)     composite load model     static load     dynamic load     induction motor load model     aggregate load    

Experimental investigation and comparative study of inter-turn short-circuits and unbalanced voltage supply in induction

Fatima BABAA, Abdelmalek KHEZZAR, Mohamed el kamel OUMAAMAR

《能源前沿(英文)》 2013年 第7卷 第3期   页码 271-278 doi: 10.1007/s11708-013-0258-6

摘要: A transient model for an induction machine with stator winding turn faults on a single phase is derived using reference frame transformation theory. The negative sequence component and the 3rd harmonic are often considered as accurate indicators. However, small unbalance in the supply voltage and/or in the machine structure that exists in any real system engenders the same harmonics components. In this case, it is too difficult to distinguish between the current harmonics due to the supply voltage and those originated by inter-turn short-circuit faults. For that, to have the correct diagnosis and to increase the sensitivity and the reliability of the diagnostic system, it is crucial to provide the relationship between the inter-turn short-circuits in the stator winding and the supply voltage imbalance through an accurate mathematical model and via a series of experimental essays.

关键词: induction machines     fault indicator     inter-turn short-circuit fault     unbalance supply voltage    

A new and best approach for early detection of rotor and stator faults in induction motors coupled to

Abderrahim ALLAL,Boukhemis CHETATE

《能源前沿(英文)》 2016年 第10卷 第2期   页码 176-191 doi: 10.1007/s11708-015-0386-2

摘要: Today, induction machines are playing, thanks to their robustness, an important role in world industries. Although they are quite reliable, they have become the target of various types of defects. Thus, for a long time, many research laboratories have been focusing their works on the theme of diagnosis in order to find the most efficient technique to predict a fault in an early stage and to avoid an unplanned stopping in the chain of production and costs ensuing. In this paper, an approach called Park’s vector product approach (PVPA) was proposed which was endowed with a dominant sensitivity in the case in which there would be rotor or stator faults. To show its high sensitivity, it was compared with the classical methods such as motor current signature analysis (MCSA) and techniques studied in recent publications such as motor square current signature analysis (MSCSA), Park’s vector square modulus (PVSM) and Park-Hilbert (P-H) (PVSM ). The proposed technique was based on three main steps. First, the three-phase currents of the induction motor led to a Park’s vector. Secondly, the proposed PVPA was calculated to show the distinguishing spectral signatures of each default and specific frequencies. Finally, simulation and experimental results were presented to confirm the theoretical assumptions.

关键词: induction motor     incipient broken bar     extended Park’s vector approach     spectral analysis     inter-turn short-circuit     Hilbert transform    

Multiple target implementation for a doubly fed induction generator based on direct power control under

Heng NIAN,Yi-peng SONG

《信息与电子工程前沿(英文)》 2015年 第16卷 第4期   页码 321-334 doi: 10.1631/FITEE.1400170

摘要: This paper presents a multiple target implementation technique for a doubly fed induction generator (DFIG) under unbalanced and distorted grid voltage based on direct power control (DPC). Based on the mathematical model of DFIG under unbalanced and distorted voltage, the proportional and integral (PI) regulator is adopted to regulate the DFIG average active and reactive powers, while the vector PI (VPI) resonant regulator is used to achieve three alternative control targets: (1) balanced and sinusoidal stator current; (2) smooth instantaneous stator active and reactive powers; (3) smooth electromagnetic torque and instantaneous stator reactive power. The major advantage of the proposed control strategy over the conventional method is that neither negative and harmonic sequence decomposition of grid voltage nor complicated control reference calculation is required. The insensitivity of the proposed control strategy to DFIG parameter deviation is analyzed. Finally, the DFIG experimental system is developed to validate the availability of the proposed DPC strategy under unbalanced and distorted grid voltage.

关键词: Direct power control     Doubly fed induction generator     Unbalanced and distorted grid voltage     Vector proportional and integral resonant regulator     Parameter deviation    

Application of fuzzy logic control algorithm as stator power controller of a grid-connected doubly-fed induction

Ridha CHEIKH, Arezki MENACER, Said DRID, Mourad TIAR

《能源前沿(英文)》 2013年 第7卷 第1期   页码 49-55 doi: 10.1007/s11708-012-0217-7

摘要: This paper discusses the power outputs control of a grid-connected doubly-fed induction generator (DFIG) for a wind power generation systems. The DFIG structure control has a six diode rectifier and a PWM IGBT converter in order to control the power outputs of the DFIG driven by wind turbine. So, to supply commercially the electrical power to the grid without any problems related to power quality, the active and reactive powers ( , ) at the stator side of the DFIG are strictly controlled at a required level, which, in this paper, is realized with an optimized fuzzy logic controller based on the grid flux oriented control, which gives an optimal operation of the DFIG in sub-synchronous region, and the control of the stator power flow with the possibility of keeping stator power factor at a unity.

关键词: doubly-fed induction generator (DFIG)     vector control     fuzzy logic controller     optimization     power factor unity     active and reactive power    

A modified neural learning algorithm for online rotor resistance estimation in vector controlled induction

A. CHITRA,S. HIMAVATHI

《能源前沿(英文)》 2015年 第9卷 第1期   页码 22-30 doi: 10.1007/s11708-014-0339-1

摘要: Online estimation of rotor resistance is essential for high performance vector controlled drives. In this paper, a novel modified neural algorithm has been identified for the online estimation of rotor resistance. Neural based estimators are now receiving active consideration as they have a number of advantages over conventional techniques. The training algorithm of the neural network determines its learning speed, stability, weight convergence, accuracy of estimation, speed of tracking and ease of implementation. In this paper, the neural estimator has been studied with conventional and proposed learning algorithms. The sensitivity of the rotor resistance change has been tested for a wide range of variation from -50% to+50% on the stability of the drive system with and without estimator. It is quiet appealing to settle with optimal estimation time and error for the viable realization. The study is conducted extensively for estimation and tracking. The proposed learning algorithm is found to exhibit good estimation and tracking capabilities. Besides, it reduces computational complexity and, hence, more feasible for practical digital implementation.

关键词: neural networks     back propagation (BP)     rotor resistance estimators     vector control     induction motor    

Toward a nonlinear control of an AC-DC-PWM converter dedicated to induction heating

Amel HADRI-HAMIDA, S. ZEROUALI, A. ALLAG

《能源前沿(英文)》 2013年 第7卷 第2期   页码 140-145 doi: 10.1007/s11708-013-0243-0

摘要: In this paper, a nonlinear control strategy applied to an AC-DC-pulse width modulation (PWM) converter is developed and simulated. First a nonlinear system modeling is derived with state variables of the input current and the output voltage by using power balance of the input and output. The system is linearized and decoupled, and then a state feedback law is obtained. For robust control of parameter perturbation, integrators are added to the exact feedback control law. The simulation is provided to verify the validity of the control algorithm.

关键词: DC-DC converter     AC-DC-pulse width modulation (PWM) converter     induction heating     nonlinear control    

Effect of ligand chain length on hydrophobic charge induction chromatography revealed by molecular dynamics

Lin ZHANG, Yan SUN

《化学科学与工程前沿(英文)》 2013年 第7卷 第4期   页码 456-463 doi: 10.1007/s11705-013-1357-y

摘要: Hydrophobic charge induction chromatography (HCIC) is a mixed-mode chromatography which is advantageous for high adsorption capacity and facile elution. The effect of the ligand chain length on protein behavior in HCIC was studied. A coarse-grain adsorbent pore model established in an earlier work was modified to construct adsorbents with different chain lengths, including one with shorter ligands (CL2) and one with longer ligands (CL4). The adsorption, desorption, and conformational transition of the proteins with CL2 and CL4 were examined using molecular dynamics simulations. The ligand chain length has a significant effect on both the probability and the irreversibility of the adsorption/desorption. Longer ligands reduced the energy barrier of adsorption, leading to stronger and more irreversible adsorption, as well as a little more unfolding of the protein. The simulation results elucidated the effect of the ligand chain length, which is beneficial for the rational design of adsorbents and parameter optimization for high-performance HCIC.

关键词: adsorption     desorption     irreversibility     protein conformational transition     molecular dynamics simulation    

Droplet spectra and high-speed wind tunnel evaluation of air induction nozzles

Qing TANG, Liping CHEN, Ruirui ZHANG, Min XU, Gang XU, Tongchuan YI, Bin ZHANG

《农业科学与工程前沿(英文)》 2018年 第5卷 第4期   页码 442-454 doi: 10.15302/J-FASE-2017169

摘要:

A series of air induction nozzles were tested in a high-speed wind tunnel. Droplet size spectra were measured for four air induction nozzles (IDK-120-01, IDK-120-02, IDK-120-03 and IDK-120-04) each at three spray pressures (0.3, 0.4 and 0.5 MPa) and seven different air velocities (121.7, 153.4, 185.5, 218.4, 253.5, 277.5 and 305.5 km·h ). The measurement distance (0.15, 0.25 and 0.35 m) from the nozzle orifice was found to be important for the atomization of the droplets. The response surface method was used to analyze the experimental data. The results indicated that v and v of the droplets decreased quasi-linearly with increased wind speed, while v was affected by the quadratic of wind speed. v , v and v of the droplets were all proportional to the orifice size, and were not markedly influenced by the spray pressure. The percentage of the spray volume consisting of droplets with a diameter below 100 mm (%<100 mm) was found to be quadratically related to wind speed, and was not markedly influenced by the spray pressure and orifice size. However, the effect of the orifice size on the %<200 mm could not be ignored.

关键词: air induction nozzle     wind tunnel     aerial spray     droplet size spectra    

Direct field oriented control scheme for space vector modulated AC/DC/AC converter fed induction motor

F. BENCHABANE, A. TITAOUINE, O. BENNIS, K. YAHIA, D. TAIBI

《能源前沿(英文)》 2012年 第6卷 第2期   页码 129-137 doi: 10.1007/s11708-012-0183-0

摘要: This paper investigates a Luenberger flux observer with speed adaptation for a direct field oriented control of an induction motor. An improved method of speed estimation that operates on the principle of speed adaptive flux and current observer has been proposed. An observer is basically an estimator that uses a plant model and a feedback loop with measured stator voltage and current. Simulation results show that the proposed direct field oriented control with the proposed observer provides good performance dynamic characteristics. The induction motor is fed by an indirect power electronics converter. This indirect converter is controlled by a sliding mode technique that enables minimization of harmonics introduced by the line converter, as well as the control of the power factor and DC-link voltage. The robustness of the overall system is studied using simulation for different operating modes and varied parameters.

关键词: induction motor     direct filed oriented control     Luenberger observer     estimation     space vector modulation (SVM)     sliding mode control     boost-rectifier    

Analysis and control of wind-driven self-excited induction generators connected to the grid through power

S. Senthil KUMAR, N. KUMARESAN, N. Ammasai GOUNDEN, Namani RAKESH

《能源前沿(英文)》 2012年 第6卷 第4期   页码 403-412 doi: 10.1007/s11708-012-0208-8

摘要: The analysis of the wind-driven self-excited induction generators (SEIGs) connected to the grid through power converters has been developed in this paper. For this analysis, a method of representing the grid power as equivalent load resistance in the steady-state equivalent circuit of SEIG has been formulated. The technique of genetic algorithm (GA) has been adopted for making the analysis of the proposed system simple and straightforward. The control of SEIG is attempted by connecting an uncontrolled diode bridge rectifier (DBR) and a line commutated inverter (LCI) between the generator terminals and three-phase utility grid. A simple control technique for maximum power point tracking (MPPT) in wind energy conversion systems (WECS), in which the firing angle of the LCI alone needs to be controlled by sensing the rotor speed of the generator has been proposed. The effectiveness of the proposed method of MPPT and method of analysis of this wind-driven SEIG-converter system connected to the grid through power converters has been demonstrated by experiments and simulation. These experimental and simulated results confirm the usefulness and successful working of the proposed system and its analysis.

关键词: self-excited induction generator (SEIG)     renewable power generation     power converters     maximum power point tracking (MPPT)     steady state analysis     power generation systems    

标题 作者 时间 类型 操作

Effects of a structurally related substance on the crystallization of paracetamol

Ali SALEEMI, I.I. ONYEMELUKWE, Zoltan NAGY

期刊论文

Constant temperature control of tundish induction heating power supply for metallurgical manufacturing

Yufei YUE, Qianming XU, Peng GUO, An LUO

期刊论文

Nucleation and growth mechanism of cefodizime sodium at different solvent compositions

Xinwei ZHANG, Shudong ZHANG, Xiaodan SUN, Zequn YIN, Quanjie LIU, Xiwen ZHANG, Qiuxiang YIN

期刊论文

Brown and beige fat: the metabolic function, induction, and therapeutic potential

null

期刊论文

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

期刊论文

Experimental investigation and comparative study of inter-turn short-circuits and unbalanced voltage supply in induction

Fatima BABAA, Abdelmalek KHEZZAR, Mohamed el kamel OUMAAMAR

期刊论文

A new and best approach for early detection of rotor and stator faults in induction motors coupled to

Abderrahim ALLAL,Boukhemis CHETATE

期刊论文

Multiple target implementation for a doubly fed induction generator based on direct power control under

Heng NIAN,Yi-peng SONG

期刊论文

Application of fuzzy logic control algorithm as stator power controller of a grid-connected doubly-fed induction

Ridha CHEIKH, Arezki MENACER, Said DRID, Mourad TIAR

期刊论文

A modified neural learning algorithm for online rotor resistance estimation in vector controlled induction

A. CHITRA,S. HIMAVATHI

期刊论文

Toward a nonlinear control of an AC-DC-PWM converter dedicated to induction heating

Amel HADRI-HAMIDA, S. ZEROUALI, A. ALLAG

期刊论文

Effect of ligand chain length on hydrophobic charge induction chromatography revealed by molecular dynamics

Lin ZHANG, Yan SUN

期刊论文

Droplet spectra and high-speed wind tunnel evaluation of air induction nozzles

Qing TANG, Liping CHEN, Ruirui ZHANG, Min XU, Gang XU, Tongchuan YI, Bin ZHANG

期刊论文

Direct field oriented control scheme for space vector modulated AC/DC/AC converter fed induction motor

F. BENCHABANE, A. TITAOUINE, O. BENNIS, K. YAHIA, D. TAIBI

期刊论文

Analysis and control of wind-driven self-excited induction generators connected to the grid through power

S. Senthil KUMAR, N. KUMARESAN, N. Ammasai GOUNDEN, Namani RAKESH

期刊论文