Microcontroller Control of Reactive Power Compensation for Growing Industrial Loads

Many industrial installations in developing countries start-up as small factories, without regard for the need of compensation of reactive power, leading to significant financial losses in the long term. By improving the power factor, the customer can reduce its power demand and potentially increase efficiency of their equipment. A PIC microcontroller is used to switch capacitor banks to compensate for the reactive power. In order to determine the size of the capacitor bank needed, the microcontroller calculates the phase difference between the voltage and the current. The results obtained based on the lagging power factor for three test loads show an improvement in the power factor from 0.52 to 0.96 under different test load conditions.

Axonal remodeling in the corticospinal tract after stroke： how does rehabilitative training modulate it？

Stroke causes long-term disability, and rehabilitative training is commonly used to improve the consecutive functional recovery. Following brain damage, surviving neurons undergo morphological alterations to reconstruct the remaining neural network. In the motor system, such neural network remodeling is observed as a motor map reorganization. Because of its significant correlation with functional recovery, motor map reorganization has been regarded as a key phenomenon for functional recovery after stroke. Although the mechanism underlying motor map reorganization remains unclear, increasing evidence has shown a critical role for axonal remodeling in the corticospinal tract. In this study, we review previous studies investigating axonal remodeling in the corticospinal tract after stroke and discuss which mechanisms may underlie the stimulatory effect of rehabilitative training. Axonal remodeling in the corticospinal tract can be classified into three types based on the location and the original targets of corticospinal neurons, and it seems that all the surviving corticospinal neurons in both ipsilesional and contralesional hemisphere can participate in axonal remodeling and motor map reorganization. Through axonal remodeling, corticospinal neurons alter their output selectivity from a single to multiple areas to compensate for the lost function. The remodeling of the corticospinal axon is influenced by the extent of tissue destruction and promoted by various therapeutic interventions, including rehabilitative training. Although the precise molecular mechanism underlying rehabilitation-promoted axonal remodeling remains elusive, previous data suggest that rehabilitative training promotes axonal remodeling by upregulating growth-promoting and downregulating growth-inhibiting signals.

An efficient dose-compensation method for proximity effect correction

A novel simple dose-compensation method is developed for proximity effect correction in electron-beam lithography.The sizes of exposed patterns depend on dose factors while other exposure parameters（including accelerate voltage,resist thickness,exposing step size,substrate material,and so on） remain constant.This method is based on two reasonable assumptions in the evaluation of the compensated dose factor：one is that the relation between dose factors and circle-diameters is linear in the range under consideration;the other is that the compensated dose factor is only affected by the nearest neighbors for simplicity.Four-layer-hexagon photonic crystal structures were fabricated as test patterns to demonstrate this method.Compared to the uncorrected structures,the homogeneity of the corrected hole-size in photonic crystal structures was clearly improved.

Transmission network expansion planning with embedded constraints of short circuit currents and N-1 security

An approach of transmission network expan-sion planning with embedded constraints of short circuit currents and N-1 security is proposed in this paper.The problem brought on by the strong nonlinearity property of short circuit currents is solved with a linearization method based on the DC power flow.The model can be converted to a mixed-integer linear programming problem,realizing the optimization of planning model that considers the constraints of linearized short circuit currents and N-1 security.To compensate the error caused by the assump-tions of DC power flow,the compensation factor is pro-posed.With this factor,an iterative algorithm that can compensate the linearization error is then presented.The case study based on the IEEE 118-bus system shows that the proposed model and approach can be utilized to:opti-mize the construction strategy of transmission lines;ensure the N-1 security of the network;and effectively limit the short circuit currents of the system.

A low-phase-noise LC-VCO with an enhanced-Q varactor for use in a high-sensitivity GNSS receiver

An LC-VCO with an enhanced quality factor（Q） varactor for use in a high-sensitivity GNSS receiver is presented.An enhanced A-MOS varactor is composed of two accumulation-mode MOS（A-MOS） varactors and two bias voltages,which show the improved Q and linearization capacitance-voltage（C-V） curve.The VCO gain（K_（vco）） is compensated by a digital switched varactors array（DSVA） over entire sub-bands.Based on the characteristics of an A-MOS,the varactor in a DSVA is a high Q fixed capacitor as it is switched off,and a moderate Q tuning varactor when it is switched on,which keeps the maximal Q for the LC-tank.The proposed circuit is fabricated in a 0.18μm 1P6M CMOS process.The measured phase noise is better than -122 dBc/Hz at a 1 MHz offset while the measured tuning range is 58.2%and the variation of K_（VCO） is close to±21%over the whole of the sub-bands and the effective range of the control voltage.The proposed VCO dissipates less than 5.4 mW over the whole operating range from a 1.8 V supply.