基于智能电表的低压电网故障预判系统

提出一种利用智能电表反馈的"失电"信息,与地理信息系统结合,通过电网拓扑分析技术,辨别配电网低压故障点的方法。通过智能电表非计量功能实现配网低压故障定位,可以提升低压用电故障处理效率,提升运营管理效能,减少电网运营成本,提高供电可靠性和用户满意度,产生显著经济效益和社会效益。

Performance of Lateral 4H-SiC Photoconductive Semiconductor Switches by Extrinsic Backside Trigger

Photoconductive semiconductor switch(PCSS)can be applied in pulsed high power systems and microwave techniques.However,reducing the damage and increasing the lifetime of silicon carbide(SiC)PCSS are still faced severe challenges.In this study,PCSSs with various structures were prepared on 4-inch diameter,500μm thick high-purity semi-insulating 4H-SiC substrates and their on-state resistance and damage mechanisms were investigated.It was found that the PCSS of an Au/TiW/Ni electrode system annealed at 950℃had a minimum on-state resistance of 6.0Ωat 1 kV bias voltage with a 532 nm and 170 mJ pulsed laser by backside illumination single trigger.The backside illumination single trigger could reduce on-state resistance and alleviate the damage of PCSS compared to the frontside trigger when the diameter of the laser spot was larger than the channel length of PCSS.For the 200 s trigger test by a 10 Hz laser,the black branch-like ablation on Au/TiW/Ni PCSS was mainly caused by thermal stress owing to hot carriers.Replacing metal Ni with boron gallium co-doped zinc oxide(BGZO)thin films annealed at 400℃,black branch-like ablation was alleviated while concentric arc damage was obvious at the anode.The major causes of concentric arc are both pulsed laser diffraction and thermal effect.

A Novel Offset-Cancellation Technique for Low Voltage CMOS Differential Amplifiers

Based on a physical understanding of nonlinearity and mismatch, a novel offset-cancellation technique for low voltage CMOS differential amplifiers is proposed. The technique transfers the offset voltage from the output to other parts of the differential amplifier and can greatly reduce the input-referred offset voltage without extra power consumption. A 1.8V CMOS differential amplifier is implemented in 0.18μm CMOS process using the proposed technique. The simulation results show that the technique could reduce the input-referred offset voltage of the amplifier by 40% with a 20% load transistor mismatch and a 10% input differential transistor mismatch. Moreover, the proposed technique consumes the least power and achieves the highest integration among various offset-cancellation techniques.

Electrophysiologic-electropharmacologic Method for Evaluating the Effects of Antagonizing Ventricular Tachyarrhythmic Drugs

Objective To establish a canine model of electrophysiologic - electropharmacology as assessed by programmed electrical stimulation (PES),and to observe the electrophysiologic effects of Procainamide(PA) on normal and ischemic myocardium in case of ischemic ventricular tachyarrhythmia in this model. Methods A ishemic ventricular tachyarrhythmias canine model was established in open-chest dogs subjected to programmed electrical stimulation(PES)for 5-8 days after acute myocardial infarction. The electrophysiologic effects of procainamide were observed in this model. With routine methods of PES,ventricular tachycardia(VT) and ventricular fibrillation (VF) could be reproducibly initiated. Results Procainamide distinctly lengthened the QTc interval (P【0.01) and effective refractory period(ERP) of normal and ischemic ventricular myocardium(NERP and IERP) respectively (P【0.01), decreased the dispersion of ERP in ischemic myocardium and the dispersion of ERP in left ventricle (P【0.01), and increased the diastolic excitability threshold of normal and ischemic ventricular myocardium remarkably (P【0.01). Procainamide effectively prevented the PES-induced VT or VF (P【0.05) and ischemia-induced VF (P【0.05). Conclusion The results indicated that PES-induced VT/VF were highly reproducible and reliable, this canine model is a worthy and reliable one, procainamide may be effective in preventing the onset of VT and VF after myocardial ischemic damage, and deserves further attention as an antifibrillatory agent.

Buckling behavior of micro metal wire on polymer membrane under combined effect of electrical loading and mechanical loading

The buckling behavior of a typical structure consisting of a micro constantan wire and a polymer membrane under coupled electrical-mechanical loading was studied. The phenomenon that the constantan wire delaminates from the polymer membrane was observed after unloading. The interfacial toughness of the constantan wire and the polymer membrane was estimated. Moreover, several new instability modes of the constantan wire could be further triggered based on the buckle-driven delamination. After electrical loading and tensile loading, the constantan wire was likely to fracture based on buckling. After electrical loading and compressive loading, the constantan wire was easily folded at the top of the buckling region. On the occasion, the constantan wire buckled towards the inside of the polymer membrane under electrical-compressive loading. The mechanisms of these instability modes were analyzed.

Wear behavior of high strength and high conductivity Cu alloys under dry sliding

In order to study the wear behavior of different kinds of contact wires,the dry sliding wear behaviors of Cu-Sn,Cu-Ag and Cu-Mg alloys prepared by up-drawn continuous casting and followed continuous extrusion were studied.The research was tested on a block-on-ring wear tester.The results indicate that the friction coefficient is remarkably influenced by the formation of a continuous tribofilm,which consists of oxidation film.The abrasion,adhesion,oxidation and plastic deformation are observed.Oxidation and abrasion wear mechanisms dominate at the lower sliding velocity and load.The combination of oxidation and adhesion play leading roles with the increasing load and velocity.Plastic deformation is detected under higher applied load and sliding velocities.

Electrophysiologic Effects of Sophoridine on a Canine Model of Ischemic Ventricular Tachyarrhythmias

A canine model of ischemic ventricular tachyarrhythmias was established in open-chest dogs subjected to programmed electrical stimulation (PES) for 5￣8 days after acute myocardial infarction. The electrophysiologic effects of sophoridine (Sop) and procainamide (PA) were observed in this canine model. With routine methods of PES, ventricular tachycardia (VT) and ventricular fibrilation (VF) could be reproducibly initiated in this model. Both drugs distinctly lengthened the QTc interval ( P <0.01) and the effective refractory period (ERP) in normal and ischemic ventricular myocardium ( P <0.01), decreased the dispersion of ERP in ischemic myocardium and the dispersion of ERP in left ventricle (P <0.05), and increased the diastolic excitability threshold of normal and ischemic ventricular myocardium remarkably ( P <0.01). Both drugs effectively prevented the PES-induced VT or VF and ischemia-induced VF ( P <0.05). The results indicated that this canine model is a good and reliable one, sophoridine and procainamide may be effective in preventing the onset of reentrant ventricular tachyarrhythmias after myocardial ischemic damage.

Application of a cost-sensitive method for churn prediction in telecommunication industry

To deal with the data mining problem of asymmetry misclassification cost, an innovative churn prediction method is proposed based on existing churn prediction research. This method adjusts the misclassification cost based on the C4. 5 decision tree as a baseline classifier, which can obtain the prediction model with a minimum error rate based on the assumption that all misclassifications have the same cost, to realize cost-sensitive learning. Results from customer data of a certain Chinese telecommunication company and the fact that the churners and the non-churners have different misclassification costs demonstrate that by altering the sampling ratio of churners and non-churners, this cost-sensitive learning method can considerably reduce the total misclassification cost produced by traditional classification methods. This method can also play an important role in promoting core competence of Chinese telecommunication industry.

Effects of acute hepatic damage on natriuresis and water excretion after acute normal saline loading in rats

AIMS To investigate the relationship between the liver function- al impairment and sodium and water retention. METHODS Acute liver damage model was established with carbon tetrachloride (CCl_4) administration to male Sprague-Daw- ley rats. Twenty-four and 48 hours later after CCl_4 administration, the excretion of acute sodium and water load was examined,and 24 hours later after normal saline administration,the excretion of acute sodium and water load was examined in control group. The concentration of plasma caffeine was analysed with high pressure liquid chromatograph (HPLC). The half life time of plasma caffein (Caft 1/2) sewed as a quantitative index of hepatic function. Plasma ALT was measured with Reitman method. The hepatic tis- sue was sectioned in the same site for water content measurement and pathological observation. The serumal and urinary sodium was measured with flame photometry. RESULTS Twenty-four hours later after CCl_4 administration, plasma alanine aminotransferase (ALT,n=6,37.5±12.6→ 189.4±34.4U,P<0.01) and water content of hepatic tissue (n =6,70.0%±1.1%→73.0%±1.0%,P<0.01) rose significantly,Caft 1/2 was prolonged significantly (94.9±18.9→ 326.4±85.8 minutes,P<0.01 ). The renal function of excretion of acute salt and water load declined obviously (n=6,Na^+: 92.4%±14.1%→50.1%±13.1%,P<0.01;H_2O:86.3%± 14.3%→42.1%±8.8%,P<0.01). Forty-eight hours later, the indexes above somewhat recovered,but were still markedly different from those of the control. Furthermore,the relationships betweenCaft 1/2 andALT (r=0.752,P<0.01),and between Caft 1/2 and excretory rate of sodium (r=-0.634,P<0.05) and water were still significant (r=-0. 612,P<0.01). CONCLUSIONS Caft 1/2 is a good index to assess the degree of hepatic damage. The hepatic dysfunction may be a factor caus- ing the renal excretory impairment to the acute sodium and water load.

The Third-Order Intermodulation Distortion in the AlGaAs/GaAs HBT Amplifier

An accurate circuit model of the microwave small signal characteristics of AlGaAs/GaAs HBT (heterojunction bipolar transistor) is extremely useful for microwave linear applications of the device. This paper presents a small signal AlGaAs/GaAs HBT equivalent circuit, based on the DC characteristics and S parameter of the device. Using Volterra series, we have calculated the third order intermodulation distortion in a linear AlGaAs/GaAs HBT amplifier. The calculations are well concordant with the measurements from two tone signals intermodulation distortion test, and its excellent third order intermodulation performance shows that AlGaAs/GaAs HBT is a very attractive candidate for linear amplification.

Beryllium-distribution in metallic glass matrix composite containing beryllium

The morphologies, sizes, compositions and volume fractions of dendritic phases in in situ Ti-based metallic glass matrix composites （MGMCs） containing beryllium （Be） with the nominal composition of Tia7Zr19Cu5V12Be17 （mole fraction, %） were investigated using XRD, SEM, EBSD, TEM, EDS and three-dimensional reconstruction method. Moreover, visualized at the nanoscale, Be distribution is confirmed to be only present in the matrix using scanning transmission electron microscopy-electron energy loss spectroscopy （STEM-EELS）. Based on these findings, it has been obtained that the accurate chemical compositions are Wi28.3Zr19.7Cu8V6.4Be37.6 （mole fraction, %） for glass matrix and Wi62.nZr18.aCu2.6V16.6 （mole fraction, %） for the dendritic phases, and the volume fractions are 38.5% and 61.5%, respectively. It is believed that the results are of particular importance for the designing of Be-containing MGMCs.

ACUPUNCTURE COMBINED WITH LANGUAGE TRAINING FOR TREATMENT OF MOTOR APHASIA CAUSED BY ISCHEMIC APOPLEXY

Objective To observe therapeutic effects of acupuncture combined with language training on aphasia induced by ischemic apoplexy and investigate the mechanisms. Methods 60 patients were randomly divided into a treatment group treated by acupuncture associated with language training and a control group treated by simple language training. Tongue-acupuncture was applied as the main therapy, and language training included speech organ training, mouth-shape and voice training, spoken language expression training and practical communication ability training. According to Aphosio Bottery of Chinese （ABC）, language ex- amination evaluation was made, and event related potential （P300） was detected before and after treatment. Results The therapeutic effect in the treatment group was significantly better than that in the control group （P〈O. 05）, and the scores of ABC items including information content, speech fluency, repetition, vocabula- ry denomination, color naming, response denomination, confirmation or negation, acoustic recognition and carrying out instruction in the treatment group were obviously higher than those in the control group （P〈0.05）. After one course of treatment, the latencies of N2 and P3 waves in P300 were significantly short- ened and the amplitude of P3 was significantly elevated in the treatment group, compared with those in the control group （P〈0.05）. Conclusion Acupuncture combined with language training provided remarkable therapeutic effects in treating cerebral infarction-induced motor aphasia, and it was better than simple lan- guage training. The results of enhancing of the ABC scores including information content, speech fluency, repetition, vocabulary denomination, color naming, response denomination, confirmation or negation, acous- tic recognition and carrying out instruction, and shortening of the latencies of N2 and P3 waves in P300 and ele- vation of P3 amplitude may be taken as the indices for evaluating and anticipating clinical therapeutic effects of the therapy for treating the disease, which may also be some of the mechanisms.

Antiarrhythmic Efficacy of Neferine Assessed by Programmed Electrical Stimulation in a Canine Model of Electropharmacology

An ishemic ventricular tachyarrhythmias canine model was established in open-chest dogs subjected to programmed electrical stimulation (PES)for 5-8 days after acute myocardial infarction. The electrophysiologic effects of neferine (Nef) and procainamide (PA) were observed in this model. With routine methods of PES,ventricular tachycardia (VT)and ventricular fibrillation (VF) could be reproducibly initiated. Both drugs lengthened the QTc interval (P【0.01) and effective refractory period(ERP)of normal and ischemic ventricular myocardia (NERP and IERP) respectively (P【0.01), decreased the dispersion of ERP in ischemic myocardium and the dispersion of ERP in left ventricle (P【0.01), and increased the diastolic excitability threshold of normal and ischemic ventricular myocardia (P【0.01). The two compounds prevented the PES-induced VT or VF (Nef group P【0.01, PA group P【0.05) and ischemia-induced VF (P【0.05). The results indicated that neferine and procainamide may be effective in preventing the onset of reentrant ventricular tachyarrhythmias after myocardial ischemic damage in dogs.

Effects of IQ_23 on the Repolarization and Both Components of the Delayed Rectifier Potassium Current in Guinea Pig Ventricular Myocytcs

Using patch clamp whole cell recording techiques, we examined the effects ofIQ_23, a benzyl-isoquinoline derivative with antiarrhythmic activities, on the action potential (AP) andpotassium currents in single guinea pig ventricular myocytes. The results showed that IQ_23 at 10, 30and 100 μmol ·L_-1 slowed the repolarization in AP dose-dependently. The APD_90 were prolonged by15%, 28% and 31% respectively. This effect did not depend on the extracellular Ca^2+. In voltageclamp mode, IQ_23 effectively blocked both the components of the delayed rectifier potassium current(I_k), i.e., I_ks and I_kr. At concentrations of 30 and 100 μmol· L^-1, IQ_23 suppressed I_ks by 21% and 26%and suppressed I_kr by 67% and 86% respectively. But even at 100 μmol·L^-1, IQ_23 had little effect onthe inward rectifier potassium current (I_k1). It is concluded: 1. IQ_23 can dose-dependently prolongAPD in the ventriculas myocytes of guinea pig, the effect does not depend on the extracellular Ca^2+; 2.IQ_23 blocks both I_ks and Ikr in the ventricular myocytes without obvious specificities between them.

Comparative Investigation of Mo（CO）6 Adsorption on Clean and OxidiZed Si（111） Surfaces

Mo（CO）6 adsorption on the clean, oxygen-precovered and deeply oxidized Si（lll） surfaces was comparatively investigated by high-resolution electron energy loss spectroscopy. The downward vibrational frequency shift of the C-O stretching mode in adsorbed Mo（CO）6 illustrates that different interactions of adsorbed Mo（CO）6 occur on clean Si（111） and SiO2/Si（111） surfaces, weak on the former and strong on the latter. The strong interaction on SiO2/Si（111） might lead to the partial dissociation of Mo（CO）6, consequently the formation of molybdenum subcarbonyls. Therefore, employing Mo（CO）6 as the precursor, metallic molybdenum could be successfully deposited on the SiO2/Si（111） surface but not on the clean Si（111） surface. A portion of the deposited metallic molybdenum is transformed into the MoOa on the SiO2/Si（111） surface upon heating, and the evolved MoO3 finally desorbs from the substrate upon annealing at elevated temperatures.

From the Gla domain to a novel small-molecule detector of apoptosis

Apoptosis plays a pivotal role in the etiology or pathogenesis of numerous medical disorders, and thus, target- ing of apoptotic cells may substantially advance patient care. In our quest for novel low-molecular-weight probes for apoptosis, we focused on the uncommon amino acid T-carboxyglutamic acid （Gla）, which plays a vital role in the binding of clotting factors to negatively charged phospholipid surfaces. Based on the alkyl-malonic acid motif of Gla, we have developed and now present ML-10 （2-（5-fluoro-pentyl）-2-methyl-malonic acid, MW=206 Da）, the pro- totypical member of a novel family of small-molecule detectors of apoptosis. ML-10 was found to perform selective uptake and accumulation in apoptotic cells, while being excluded from either viable or necrotic cells. ML-10 uptake correlates with the apoptotic hallmarks of caspase activation, Annexin-V binding and disruption of mitochondrial membrane potential. The malonate moiety was found to be crucial for ML-10 function in apoptosis detection. ML- 10 responds to a unique complex of features of the cell in early apoptosis, comprising irreversible loss of membrane potential, permanent acidification of cell membrane and cytoplasm, and preservation of membrane integrity. ML-10 is therefore the most compact apoptosis probe known to date. Due to its fluorine atom, ML-10 is amenable to radio- labeling with the lSF isotope, towards its potential future use for clinical positron emission tomography imaging of apoptosis.

Study on the failure mechanism of Ag-Ce contacts in DC level

Nominal contact resistance, minimum erosion and material transfer are required with low cost materials working in a wide currents range for DC relays. Ag-Ni contact materials have low contact resistance, but the erosion and material transfer are large at high current level. Ag-SnO2 contact materials have good anti-welding properties and resistance to arc erosion, but they have large contact resistance during working and are easily block SnO2 from flocking together on the surface at low current level. In this paper, the failure mechanisms of Ag-Ce contact material were studied. The surface morphologies of the contacts after electrical endurance test for Ag-Ce contact material were compared with that of Ag-Ni and Ag-SnO2 contact materials. The effect of Ce on the surface morphologies of the contacts after electrical endurance test was analyzed.

DAMAGES AND FAILURES OF SMART STRUCTURES

According to some observed dama ge phenomena in the smart structure systems, the issues related to the damage and failures of smart structures are addressed in this paper. A few possible damage patterns and the definition of the failure of the smart structures are given. It is pointed out that more attentions should be paid to the functional failures o f smart structures. The effects on the control the static deformation due to par tial debonding of PZT actuators are analyzed by the finite element method. Preli minary numerical results show that partial debonding of PZT actuators may have a p preciate reduction on their actuating ability thus reducing the control ability and accuracy of the smart structures.

Study on reliability technology of contactor relay

In this paper, the reliability of contactor relay is studied. There are three main parts about reliability test and analysis. First, in order to analyze reliability level of contact relay, the failure ratio ranks are established as index base on the product level. Second, the reliability test method is put forward. The sample plan of reliability compliance test is gained from reliability sample theory. The failure criterion is ensured according to the failure modes of contactor relay. Third, after reliability test experiment, the analysis of failure physics is made and the failure reason is found.

Effects of allitridum on the transient outward potassium current in rats with heart failure

Objective To study the effect of allitridum on the transient outward potassium current （Ito） of ventricular myocytes in heart failure （HF）. Methods The dual enzymatic method was used to separate single ventricular myocytes from Sprague Dawley rats. Patch-clamping was used to record Ito and analyze the effect of allitridum on the current. Results The Ito current had a significant decrease in the HF group, compared with the control group. The density of Ito in the HF group was increased after treatment of allitridum （30 μmol/L）. The peak current densities of Ito were enhanced in the HF group from 6.01 ±0.30 pA/pF to 8.41 ±0.54 pA/pF （P 〈 0.01） at ＋50 mV after treatment with allitridum （30 μmol/L）. We also determined the effect of allitridum on the gating mechanism of the Ito in the HF group. Conclusions We found that allitridum increased the Ito by accelerating the activation of channels and shortened the time constants of inactivation, and allitridum decreased the remodeling of Ito in ventricular myocytes of rats with HF.