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Now showing items 1 - 16 of 401

  • Study on the performance of an open-loop passive containment cooling system

    Jinhua Bai   Bo Zhao   Jianjun Wang  

    The containment is an ultimate and important barrier to keep the radioactivity from release. The integrity of the containment is crucial to control the consequences of either loss of coolant accident or main steam line break accident. A passive containment cooling system concept designed to remove the heat by natural circulation means is proposed, which is composed of a series of heat exchangers, long connecting pipes with relative large diameter, valves, and a water tank. The performance of the system is numerically simulated and the self-developed codes are validated by the experimental data. The influences of several key parameters are investigated on the performance of the system from different aspects. The results confirm that four distinct operating stages could be experienced as follows: startup stage, single-phase quasi-steady stage, flashing speed up transient stage, and flashing dominated quasi-steady operating stage. Furthermore, the mechanisms of the ways through which the parameters influence the behaviors of the proposed system are thus analyzed. Moreover, the feasibility of the system is also commented on the basis of the numerical results.
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  • Aero engine rotor air floatation assembling device based on gantry structure

    An aero engine rotor air floatation assembling method and device based on a gantry structure belong to mechanical assembling technology. The present invention can effectively solve the problem of poor coaxality after the aero engine rotor is assembled and has the characteristics of high coaxality after the rotor is assembled, reduced vibration, mounting easiness, high flexibility and improved engine performance. The measuring method and device are: determining rotary reference based on a rotary air bearing; determining the angular positioning of a rotary table according to a grating ruler; extracting the radial error of the radial mounting plane and the inclination error of the axial mounting plane of the rotor based on the four-probe measuring device to obtain the influencing weight of this rotor to the assembled rotor on coaxality; measuring respectively all the rotors required for assembling to obtain the influencing weight of each rotor to the assembled rotor on coaxality; vector optimizing the weight of each rotor to obtain the assembling angle of each rotor.
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  • Image processing method for dynamically adjusting luminance and contrast of image

    An image processing method for adjusting the luminance and contrast of an input image comprises the following steps. First, local spatial luminance statistics is performed on the first pixels of the input image to generate a luminance image including a plurality of second pixels. Then, from a preset mapping curve group comprising a plurality of smooth mapping curves, a corresponding smooth mapping curve is selected for each of the second pixels according to an adjusting function. Next, the pixel values of the second pixels are adjusted according to the corresponding smooth mapping curves to generate an adjusted image.
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  • WiFi client with hybrid communication capabilities for wireless local area network

    A hybrid wireless client apparatus including: a hybrid client controller, at least one antenna, and a plurality of shared and discrete components coupled to one another to form at least one transmit and receive chain each coupled to the at least one antenna for orthogonal frequency division multiplexed (OFDM) wireless communications with a wireless access point (WAP). The hybrid client controller is coupled to the plurality of shared and discrete components and configured to determine an eligibility of at least one neighboring wireless client node on a wireless local area network (WLAN) as a relay target, and responsive to an affirmative eligibility determination to initiate on the hybrid wireless client apparatus both local communications with the WAP together with a relay of distinct communications between the WAP and the at least one neighboring wireless client node as the relay target.
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  • Preparation method for implantable medical biological materials of animal origin

    The present invention provides a preparation method for implantable medical biological material of animal origin comprising the following procedures: Pre-processing, and washing of animal tissue materials; inactivation of virus; decellularizing cell; sodium chloride processing; molding and packaging sterilization. Cell-free ECM materials of animal origin produced by this method can achieve the goal of completely removing cell components of animal origin and composition of DNA, and at the same time, the natural ECM composition, three-dimensional structure and active growth factor which can induce and promote tissue regeneration retain. By using this process, endotoxin, organic solvents and toxic solvent residue are thus omitted and products with different sizes, thickness and mechanical strength can be formed.
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  • Parametric modeling of implied smile functions: a generalized SVI model

    Bo Zhao   Stewart D. Hodges  

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  • A new distribution vector and its application in genome clustering

    Bo Zhao   Rong L. He   Stephen S.-T. Yau  

    In this paper we report a novel mathematical method to transform the DNA sequences into the distribution vectors which correspond to points in the sixty dimensional space. Each component of the distribution vector represents the distribution of one kind of nucleotide in k segments of the DNA sequences. The mathematical and statistical properties of the distribution vectors are demonstrated and examined with huge datasets of human DNA sequences and random sequences. The determined expectation and standard deviation can make the mapping stable and practicable. Moreover, we apply the distribution vectors to the clustering of the Haemagglutinin (HA) gene of 60 H1N1 viruses from Human, Swine and Avian, the complete mitochondrial genomes from 80 placental mammals and the complete genomes from 50 bacteria. The 60 H1N1 viruses, 80 placental mammals and 50 bacteria are classified accurately and rapidly compared to the multiple sequence alignment methods. The results indicate that the distribution vectors can reveal the similarity and evolutionary relationship among homologous DNA sequences based on the distances between any two of these distribution vectors. The advantage of fast computation offers the distribution vectors the opportunity to deal with a huge amount of DNA sequences efficiently.
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  • Video encoder instances to encode video content via a scene change determination

    Methods and systems may provide for invoking instances of a hardware video encoder, wherein the instances include a first encoder instance and a second encoder instance. Additionally, the first encoder instance may be used to make a scene change determination and a motion level determination with respect to the video content. In one example, the second encoder instance is used to encode the video content based on the scene change determination and the motion level determination.
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  • Monopoly and Economic Efficiency: Perspective from an Efficiency Wage Model

    Bo Zhao  

    The objective of this paper is to analyze the efficiency consequences of monopoly from the perspective of an efficiency-wage model based on Shapiro and Stiglitz (1984). An important innovation of our model is that a firm can raise the probability that a shirking worker is detected by increasing its effort or investment in the monitoring of workers. By comparing with the competitive equilibrium we find that monopoly is associated with higher unemployment rate and less monitoring. Surprisingly, however, monopoly is not necessarily dominated by perfect competition in terms of economic efficiency.
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  • Pneumatic-type precision annular workpiece inner positioning surface clamping device

    A pneumatic-type precision annular workpiece inner positioning surface clamping device, wherein a rod portion of a piston assembly (5) is inserted into a central hole of the wedge-shaped block (12), and the piston portion of the piston assembly (5) is located in a closed chamber of a cylinder body (15); a disc spring (3) is sleeved on the piston assembly (5); an air intake hole (1-1) is provided in the lower plate (1), an air vent hole (15-1) is provided at the upper portion of the cylinder body (15); and an elastic hinge block (6) is sleeved outside the wedge-shaped block (12). The pneumatic-type precision annular workpiece inner positioning surface clamping device has a simple structure, high reliability and strong adaptability.
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  • Performance Analysis of Spectrum Sensing With Multiple Primary Users

    Bo Zhao   Yunfei Chen   Chen He   Lingge Jiang  

    The effect of multiple primary users on spectrum-sensing performance is investigated. Different models for primary user traffic are considered. The effects of different system parameters on sensing accuracy are examined. Numerical results show that the spectrum-sensing performance is significantly degraded by the primary user traffic and that the degradation decreases when the number of primary users increases.
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  • A PLL based WSN transmitter and I/Q LO signal generator at 430–435

    Bo Zhao   Lei Guo   Huazhong Yang   Hui Wang  

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  • Hard-Input–Hard-Output Capacity Analysis of UWB BPSK Systems With Timing Errors

    Bo Zhao   Yunfei Chen   Green, R.  

    The hard-input-hard-output capacity of a binary phase-shift keying (BPSK) ultrawideband system is analyzed for both additive white Gaussian noise and multipath fading channels with timing errors. Unlike previous works that calculate the capacity with perfect synchronization and/or multiple-access interference only, our analysis considers timing errors with different distributions, as well as the interpath (IPI), interchip (ICI), and intersymbol (ISI) interferences, as in practical systems. The sensitivity of the channel capacity to the timing error is examined. The effects of pulse shape, the multiple-access technique, the number of users, and the number of chips are studied. It is found that time hopping is less sensitive to the pulse shape and that the timing error has higher capacity than direct sequence due to its low duty of cycle. Using these results, one can choose appropriate system parameters for different applications.
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  • Study on corrosion in CO2 chemical absorption process using amine solution

    Bo Zhao   Yuekun Sun   Yang Yuan   Jubao Gao   Shujuan Wang   Yuqun Zhuo   Changhe Chen  

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  • Reforming Municipal Aid in Massachusetts: The Case for a Gap-Based Formula

    Bo Zhao   David Coyne  

    Massachusetts needs a more rational, work- able, and transparent system for distributing municipal aid. Many communities in the state have large municipal gaps caused by factors beyond their control, and the current distribu- tion of municipal aid does not closely relate to those gaps. Our simulation shows that a gap-based formula can significantly improve the distribu- tion of municipal aid in a relatively short time period, despite limited resources. Such a for- mula does so without considering local policies or redistributing current aid. Implementing such a gap-based formula would provide Mas- sachusetts with the tools it needs to alleviate the fiscal challenges its communities face, and help equalize the ability to provide municipal services across cities and towns.
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  • A novel clustering method via nucleotide-based Fourier power spectrum analysis

    Bo Zhao   Victor Duan   Stephen S.-T. Yau  

    A novel clustering method is proposed to classify genes or genomes. This method uses a natural representation of genomic data by binary indicator sequences of each nucleotide (adenine (A), cytosine (C), guanine (G), and thymine (T)). Afterwards, the discrete Fourier transform is applied to these indicator sequences to calculate spectra of the nucleotides. Mathematical moments are calculated for each of these spectra to create a multidimensional vector in a Euclidean space for each gene or genome sequence. Thus, each gene or genome sequence is realized as a geometric point in the Euclidean space. Finally, pairwise Euclidean distances between these points (i.e. genome sequences) are calculated to cluster the gene or genome sequences. This method is applied to three sets of data. The first is 34 strains of coronavirus genomic data, the second is 118 of the known strains of Human rhinovirus (HRV), and the third is 30 bacteria genomes. The distance matrices are computed based on the three sets, showing the distances from each point to the others. We used the complete linkage clustering algorithm to build phylogenetic trees to indicate how the distances among these sequence correspond to the evolutionary relationship among these sequences. This genome representation provides a powerful and efficient method to classify genomes and is much faster than the widely acknowledged multiple sequence alignment method.
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