A complete small-signal HBT model including AC current crowding effect

An improved small-signal equivalent circuit of HBT concerning the AC current crowding effect is proposed in this paper. AC current crowding effect is modeled as a parallel RC circuit composed of Cbi and Rbi, with distributed base-collector junction capacitance also taken into account. The intrinsic portion is taken as a whole and extracted directly from the measured Sparameters in the whole frequency range of operation without any special test structures. An HBT device with a 2 × 20 μm^(2) emitter-area under three different biases were used to demonstrate the extraction and verify the accuracy of the equivalent circuit.

Characterization of the current crowding effect on chip surface using a quantum wide-field microscope

We characterize the current crowding effect for microwave radiation on a chip surface based on a quantum wide-field microscope combining a wide-field reconstruction technique. A swept microwave signal with the power of 0–30 d Bm is supplied to a dumbbell-shaped microstrip antenna, and the significant differences in microwave magnetic-field amplitudes attributed to the current crowding effect are experimentally observed in a 2.20 mm ×1.22 mm imaging area. The normalized microwave magnetic-field amplitude along the horizontal geometrical center of the image area further demonstrates the feasibility of the characterization of the current crowding effect. The experiments indicate the proposal can be qualified for the characterization of the anomalous area of the radio-frequency chip surface.

Effects of Shape of Crowders on Dynamics of a Polymer Chain Closure

Using 3D Langevin dynamics simulations, we investigate the effects of the shape of crowders on the dynamics of a polymer chain closure. The chain closure in spherical crowders is dominated by the increased medium viscosity so that it gets slower with the increasing volume fraction of crowders. By contrast, the dynamics of chain closure becomes very complicated with increasing volume fraction of crowders in spherocylindrical crowders. Notably, the mean closure time is found to have a dramatic decrease at a range of volume fraction of crowders 0.36-0.44. We then elucidate that an isotropic to nematic transition of spherocylindrical crowders at this range of volume fraction of crowders is responsible for the unexpected dramatic decrease in the mean closure time.

PERSISTENCE AND THE GLOBAL DYNAMICS OF THE POSITIVE SOLUTIONS FOR A RATIODEPENDENT PREDATOR-PREY SYSTEM WITH A CROWDING TERM IN THE PREY EQUATION

This paper deals with the global dynamical behaviors of the positive solutions for a parabolic type ratio-dependent predator-prey system with a crowding term in the prey equation, where it is assumed that the coefficient of the functional response is less than the coefficient of the intrinsic growth rates of the prey species. We demonstrated some special dynamical behaviors of the positive solutions of this system which the persistence of the coexistence of two species can be obtained when the crowding region in the prey equation only is designed suitably. Furthermore, we can obtain that under some conditions, the unique positive steady state solution of the system is globally asymptotically stable.

Effect of pad geometry on current density and temperature distributions in solder bump joints

Three-dimensional thermo-electrical finite element analyses were conducted to simulate the current density and temperature distributions in solder bump joints with different pad geometries.The effects of pad thickness,diameter and shape on current density and temperate distributions were investigated respectively.It was found that pads with larger thickness or/and diameter could reduce current density and temperature in solder bump significantly.Pad shapes affected the current density and temperature distributions in solder bumps.The relatively low current density and temperature didn＇t occur in the bump joint with traditional rounded pad but occurred in bump joints with octagonal and nonagonal pads respectively.Therefore,optimized pad geometry may be designed to alleviate the current crowding effect and reduce the bump temperature,and therefore delay electromigration failure and increase the mean-time-to-failure.

Molecular crowding electrolytes for stabilizing Zn metal anode in rechargeable aqueous batteries

A solid electrolyte interphase(SEI)with a robust mechanical property and a high ionic conductivity is imperative for high-performance zinc metal batteries.However,it is difficult to form such a SEI directly from an electrolyte.In this work,a molecular crowding effect is based on the introduction of Zn(OTF)_(2)and Zn(ClO_(4))_(2)to 2 mol/L ZnSO_(4)electrolytes.Simulations and experiments indicate that the Zn(OTF)_(2)and Zn(ClO_(4))_(2)not only create a molecularly crowded electrolyte environment to promote the interaction of Zn^(2+)and OTF^(-),but also participate in the reduction to construct a robust and high ionic-conductive SEI,thus promoting metal zinc deposition to the(002)crystal surface.With this molecular crowding electrolyte,a high current density of 1 mA/cm^(2)can be obtained by assembling symmetric batteries with Zn as the anode for over 1000 h.And in a temperature environment of-10℃,a current density of 1 mA/cm^(2)can be obtained by assembling symmetric batteries with Zn for over 200 h.Zn//Bi_(2)S_(3)/VS4@C cells achieve a CE rate of up to 99.81%over 1000 cycles.Hence,the utilization of a molecular crowding electrolyte is deemed a highly effective approach to fabricating a sophisticated SEI for a zinc anode.

Study of Magnetic Force Distribution for Electromagnetic V-shape Bending Forming of Small Size Flat Sheet

Electromagnetic V-shape bending of small size sheet blank is investigated numerically and experimentally. Three-dimensional electromagnetic field models are established to calculate the magnetic force distribution on the sheet by software ANSYS / EMAG. Series of electromagnetic V-shape bending forming experiments are presented,in which small size uniform pressure coil and big size round flat spiral coil are used. The results show that small size uniform pressure coil is not suitable for electromagnetic forming of small size flat sheet,and the coil is susceptible to failure such as bulging,ablation and cracking. When the plane dimension of round flat spiral coil is bigger than sheet blank sizes,the induced current crowding effect will be resulted which seriously influence the magnetic force distribution on the sheet. In this case,magnetic force distribution can be adjusted through the change of the relative position between coil and sheet,the desired deformation can be obtained finally. Therefore,big size round flat spiral coil can be well applied to electromagnetic V-shape bending forming of small size flat sheet.

Influence of government subsidies on western enterprise technology innovation

With the deepening of the western development,supports of the country for the western region of China continued to increase.It also includes the support for enterprise innovation activities,by reducing the tax,exemption,subsidies and other means.Due to the effect of government subsidies on enterprise innovation activities is different in different regions,industries and so on,there is a big controversy.Therefore,we use the panel data of listed companies in manufacturing industry of western region as samples for empirical research,to research the effect of government subsidies on enterprise innovation activities in the western of China,the study found that overall,the current government subsidies has a positive effect on Enterprise R&D investment,whereas the last year's government subsidy has a negative effect on R&D investment,but it's incentive effect is greater than the crowding out effect.The study also found there are different effects between the state-owned enterprises and private enterprises,the crowding out effect of private enterprises is very small and not significant.

Study on Ecological Strategy of Enterprises' Competition

The ecolotogical research of enterprises＇ competition is the front line of current research of enterprises ＇ competition strategy ： This text applies the competition principle of living creature in ecology to research enterprises＇ competition problems .explains the ecological characterisiics of enterprises＇ competition, such as non-symmetry, crowded effect, density effect. competition-rejective effect, suitable resources niche and red queen effect etc., deduces the ecological model of enterprise＇ competition, and further analyzes enterprises＇ competition strategy; strategy R and strategy K. on the basis of enterprises＇ practices, Therefore enterprises＇ competition ecosystem theories have further been deepened and enriched.

IS-LM Model Based Analysis on the Role of China's Financial Policy for Supporting Agriculture

The"three rural"issues have always been an important and prominent issue in China's economy and society.The"No.1 Document"of the central government of China over the years has all stressed this field.The state has also undertaken various economic policies to increase the income of rural residents,support agricultural development,and improve rural infrastructure construction.Among the various policies,financial support for agriculture is a frequently used macroeconomic policy.Based on the IS-LM model,this paper analyzed the effects of financial policy for supporting agriculture on the IS-LM model,discussed the specific role of the financial policy,in order to provide a certain reference for the government to better use financial policy to support the agriculture.

Design of MCI single and symmetrical on-chip spiral inductors

In this paper,the MCI（multipath crossover interconnection）technique for octagon single and symmetrical spiral inductors has been presented to improve the quality factor.The metal wires of the single and symmetrical inductors formed by the top metal are divided into multiple segments according to the depth of the skin effects.The outermost path of the metal is crossover-interconnected to the innermost path by the underlayer metal and via The crossover technique makes the lengths of the total current paths between two ports approximately equal to each other.Therefore,the induced magnetic flux and resistance of each path can be balanced and the Q-factor of spiral inductors can be enhanced.The proposed MCI technique has been validated by the electromagnetic simulation with the 130-nm 1P6M SiGe BiCMOS process.For the devices with occupying areas of 240 240 μm^2,results of electromagnetic simulation show that about 24%improvement in the Q-peak（3.3 GHz）of the MCI single inductor as compared to conventional single inductors（3.1 GHz）,and about 88.1%improvement in the Q-peak（3.2 GHz）of the MCI symmetrical inductor as compared to conventional symmetrical inductors（1.8 GHz）.

Molecular diffusion in ternary poly(vinyl alcohol)solutions

The diffusion kinetics of a molecular probe-rhodamine B-in ternary aqueous solutions containing poly(vinyl alcohol),glycerol,and surfactants was investigated using fluorescence correlation spectroscopy and dynamic light scattering.We show that the diffusion characteristics of rhodamine B in such complex systems is determined by a synergistic effect of molecular crowding and intermolecular interactions between chemical species.The presence of glycerol has no noticeable impact on rhodamine B diffusion at low concentration,but significantly slows down the diffiision of rhodamine B above 3.9%(w/v)due to a dominating steric inhibition effect.Furthermore,introducing surfactants(cationic/nonionic/anionic)to the system results in a decreased diffusion coefficient of the molecular probe.In solutions containing nonionic surfactant,this can be explained by an increased crowding effect.For ternary poly(vinyl alcohol)solutions containing cationic or anionic surfactant,surfactant-polymer and surfactant-rhodamine B interactions alongside the crowding effect of the molecules slow down the overall diffiisivity of rhodamine B.The results advance our insight of molecular migration in a broad range of industrial complex formulations that incorporate multiple compounds,and highlight the importance of selecting the appropriate additives and surfactants in formulated products.

The Potential of Industrial Agglomeration to Promote Pharmaceutical Innovation: Analysis of China's “Medicine Valley” Construction Upsurge

This paper reports the innovation effect of pharmaceutical industry agglomeration from the perspective of patterns of agglomeration and innovation,by using registration application data for innovative and generic drugs as indicators of pharmaceutical innovation.First,the distribution of the pharmaceutical industry in China is characterized by high agglomeration and low innovation.Second,no significant infuence is exerted by regional industrial and development zone agglomeration on the development of innovative drugs in different regions;the effect of the promotion of generic drugs is reflected mainly in the location entropy index.Third,the existence of a crowding effect weakens the effect of the promotion of agglomeration on pharmaceutical innovation and the adverse impact on innovative drugs is significantly greater than the effect on generic drugs.In further research,we explored the bias effect of agglomeration in development zones and the synergistic effects of different agglomeration models.It is difficult to improve the quality of independent innovation by spatial agglomeration.Government-led development zones play a rather limited role in pharmaceutical innovation.

Which Strategy Maximizes the Innovation Output of Firms in China:Using a Control or an Entrepreneurial Sphere?

Innovation is a key stimulus for firms’survival and growth.However,many of Chinese firms fail to make it due to the lack of adequate financial resources.Previous studies have been deeply investigated the relationships between financial resources and firms’innovation performance.This paper extends such stream of the literature by focusing on a vital question for entrepreneurs:how to maximize innovation output under resource constraints.Based on an extensive dataset collected at Zhongguancun Science Park(ZSP),Beijing,China,over the period 2011-2014,this paper discusses whether entrepreneurs should pursue extra public funding(control sphere).Besides,this paper also provides empirical evidence for entrepreneurs to make proper choices about resource allocation(entrepreneurial sphere).This paper hypothesizes that enterprises allocating resources by using the entrepreneurial sphere,rather than the control sphere,can advance innovation output.To test our hypothesis,this paper adopts a dynamic panel model estimated by a bootstrapbased bias correction procedure.We find that,in advancing innovative performance,the entrepreneurial sphere is more effective than control.Indeed,at the overall level,the crowding out effect merely offsets the additionality effect when enterprises pursue extra public funding.Therefore,the control sphere does not play an essential role in advancing innovation performance.Thus,extra efforts in that direction will turn out to be in vain.Consequently,as a policy implication we claim that entrepreneurs should spend more time and energy on productive activities rather than lobbying and rent-seeking.In addition,managers should allocate resources properly for internal knowledge creation,external knowledge absorption and S&T activities.