Sun H.,Lanzhou University of Technology
ACM International Conference Proceeding Series | Year: 2016
With widely application of large-scale wireless communication system, the spatial location of the user and the access point is often not completely regular. The intensity of the interference and the signal received by the receiver are all directly rely on the position of the node, and the spatial topology of the wireless Ad-Hoc network and its change are the key factors that affect network performance. The probability distribution is established when the nodes are mobile in wireless Ad-Hoc networks. Using angle θn to explain the different motion direction of the nodes, and the probability distribution function is derived from the node continuous motion angle difference Φn s a random variable. In the evaluation of interference, the interference distance is used as the basis of the assessment. Therefore, defining interference coefficient β to establish interference assessment scope, to analyze the intensity of interference between different links through the relationship between the distance of the sender node in interference link to receiving node in estimation link and interference assessment scope. And, the distribution function of the interference in wireless Ad-Hoc networks is derived with the random variable φn. Then the reliability and universality of the model are illustrated by numerical simulation. © 2016 ACM.
News Article | February 22, 2017
To soothe aches and pains, many people turn to heating pads, patches or creams. Although a common practice, thermotherapy can cause burns. Now researchers are developing a transparent heating pad that allows users to see through it to monitor their skin's color and prevent such injuries. They report their approach in the journal ACS Applied Materials & Interfaces. Thermotherapy pads help treat a range of conditions including rheumatoid arthritis. But they've been known to cause burns, particularly among people who fall asleep with their heating pads on or among the elderly or others who might not be very sensitive to heat. Part of the problem is that commercial heating pads are opaque, and users can't see how their skin is reacting to the therapy. Other researchers have developed transparent alternatives, but they were ultimately too stiff, costly or brittle. Wei Lan and colleagues wanted to address this problem by developing a flexible, see-through device. To make their thermotherapy pad, the researchers embedded conductive silver nanowires in a thin polyvinyl alcohol film. They then enveloped the film and a copper electrode in biocompatible polydimethylsiloxane, a type of silicone, to insulate the heating element and protect a user's skin. Testing showed that the transparent device heated quickly when 3 volts were applied, which is the typical voltage of coin-cell batteries used in watches, remotes and other small electronics. It was also very flexible and worked well even after being bent 10,000 times. The authors acknowledge funding from the Natural Science Foundation of Gansu Province, the State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology and the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry. See how the heating pad works in this Headline Science video. The abstract that accompanies this study is available here. The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With nearly 157,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies. Its main offices are in Washington, D.C., and Columbus, Ohio. To automatically receive news releases from the American Chemical Society, contact firstname.lastname@example.org.
Wang Y.,Lanzhou University of Technology
International Journal of Innovative Computing, Information and Control | Year: 2016
Deep Belief Networks (DBNs) method ignores the image local structure and is difficult to learn the local characteristics of face image, the network training time is also too long to make full use of the facial texture feature and reduce the bad influence of illumination, and a novel method by fusing Local Binary Pattern (LBP) and DBNs features is proposed in this paper. In this method, the LBP feature is as the input of the DBNs. Furthermore, in order to accelera, te the training speed of DBNs, the Extreme Learning Machine (ELM) is introduced into the network training process. Finally, the training network is used to classify and recognize. Experiments on ORL and FERET face databases with different resolution demonstrate that the proposed method is better than other relevant methods. © 2016, IJICIC Editorial Office. All rights reserved.
Zhou Y.,Lanzhou University of Technology |
Lin Q.,Lanzhou University of Technology
Journal of Alloys and Compounds | Year: 2014
Zn coating is essential for joining Al to galvanized steel by cold metal transfer (CMT) method; however the role of Zn on the wetting mechanism is still ambiguous. We recorded the first cycle for the molten metal transferring process using a high speed video camera, and further analyzed the wetting behavior and the interfacial microstructures. The results indicated that the significant contribution of Zn coating for the wetting is the reserved metallic characteristic of the galvanized steel surface after Zn evaporation. The residual liquid Zn film after evaporation could not improve the final wettability, and also should not be a driving force for spreading but may be a factor for contact angle hysteresis. Finally, a Zn rich zone was formed by the different affinity of Al-Fe, Zn-Fe and Al-Zn in thermodynamically, i.e., high affinity of Al-Fe and relative weak affinity of Zn-Fe and Zn-Al, and then the residual liquid Zn film was driven by the moving of molten Al alloys. © 2013 Elsevier B.V. All rights reserved.
Li W.-G.,Lanzhou University of Technology
International Journal of Rotating Machinery | Year: 2013
Slip factor is an important parameter in the hydraulic design of centrifugal pump impeller for handling viscous oils. How to extract the factor from CFD computational results and how flow rate and liquid viscosity to affect it remain unclear. In the present paper, the flip factor was estimated by means of two approaches: one is from the velocity triangles at the impeller outlet and the other is due to the impeller theoretical head of 3D turbulent viscous fluid. The velocity of water and viscous oils in the impeller and volute computed by CFD was validated with LDV measurements at the best efficiency point. The effect of exit blade angle on slip factor was clarified. It was shown that the two approaches result into two different slip factors. The factors are significantly dependent of flow rate; however, the liquid viscosity seems to take less effect on them. Volute is responsible for reduction in tangential velocity of liquid at the outlet of impeller at low flow rates. The slip factor of impeller with large exit blade angle is not sensitive to flow rate. © 2013 Wen-Guang Li.
Li W.,Lanzhou University of Technology
Journal of Fluids Engineering, Transactions of the ASME | Year: 2013
A series of experiments has been conducted to identify the effects of both fluid viscosity and wear-rings gap on the performance of a low specific speed industrial centrifugal pump of type 65Y60 for transporting viscous oils by the author group. Unfortunately, the experimental results remained unexplained on a fluid dynamics base. To remedy this problem, a highly viscous oil flow model and computational method in the side chambers in that pump were proposed based on the existing theoretical and experimental results. The flow coupling between the chambers and the gaps of the wear-rings and/or the balance holes was realized. The model was validated by making use of the existing experiment data in the chamber between a rotating disk and the walls of a stationary cylindrical container. Then the flow model was applied into the two side chambers in that pump when the wear-rings clearances and liquid viscosity were changed. The results demonstrated that the flow model is sensitive to wear-rings gap, liquid viscosity, the roughness of the wet walls of the chambers, and leakage flow rate. For this pump, an enlarged clearance can improve the mechanical efficiency, but the increment in the efficiency is unable to compensate for the considerable drop in the volumetric efficiency, causing the gross efficiency not be improved, especially at a high viscosity. Copyright © 2013 by ASME.
Wu X.,Lanzhou University of Technology |
Ma J.,Lanzhou University of Technology
PLoS ONE | Year: 2013
A regular network of neurons is constructed by using the Morris-Lecar (ML) neuron with the ion channels being considered, and the potential mechnism of the formation of a spiral wave is investigated in detail. Several spiral waves are initiated by blocking the target wave with artificial defects and/or partial blocking (poisoning) in ion channels. Furthermore, possible conditions for spiral wave formation and the effect of partial channel blocking are discussed completely. Our results are summarized as follows. 1) The emergence of a target wave depends on the transmembrane currents with diversity, which mapped from the external forcing current and this kind of diversity is associated with spatial heterogeneity in the media. 2) Distinct spiral wave could be induced to occupy the network when the target wave is broken by partially blocking the ion channels of a fraction of neurons (local poisoned area), and these generated spiral waves are similar with the spiral waves induced by artificial defects. It is confirmed that partial channel blocking of some neurons in the network could play a similar role in breaking a target wave as do artificial defects; 3) Channel noise and additive Gaussian white noise are also considered, and it is confirmed that spiral waves are also induced in the network in the presence of noise. According to the results mentioned above, we conclude that appropriate poisoning in ion channels of neurons in the network acts as 'defects' on the evolution of the spatiotemporal pattern, and accounts for the emergence of a spiral wave in the network of neurons. These results could be helpful to understand the potential cause of the formation and development of spiral waves in the cortex of a neuronal system. © 2013 Wu, Ma.
Jianguo Q.,Lanzhou University of Technology
Mechanism and Machine Theory | Year: 2010
Based on general profile theory, the basic scroll profiles are presented in the form of polynomial or simple trigonometric functions. For a scroll fluid machine with an arbitrary number of scroll wraps on its individual scroll, the phase difference between adjacent scroll profiles is defined as the characteristic angle and its scroll pitch lines are classified into A-type and B-type. The normal thickness and the all-thickness of scroll wrap are also defined. The number of scroll wraps on one scroll, the orbiting radius, the maximum tangential component of general profile, the thickness coefficient, and the height of scroll wrap are determined as the basic parameters which can demonstrate basic characteristics of scroll fluid machine. It is more reasonable to employ involute of circle and double-wrap scroll, to specify a smaller orbiting radius and a smaller height under satisfaction of the basic requirement. According to the basic parameters proposed, scroll fluid machine is classified into small-parameter and large-parameter scroll fluid machines. In order to obtain the performance with higher working pressure and larger compression ratio, it may be a significant work to study the large-parameter scroll fluid machine. © 2009 Elsevier Ltd. All rights reserved.
Jianguo Q.,Lanzhou University of Technology
Journal of Fluids Engineering, Transactions of the ASME | Year: 2010
For a scroll fluid machine with an arbitrary number of scroll wraps on its individual scroll, the phase difference between adjacent scroll profiles on one scroll is defined as the characteristic angle of the scroll. Based on general profile theory, a scroll pitch line is defined as of A-type with which the outer profile of orbiting scroll and the inner profile of fixed scroll can be formed. Another scroll pitch line is defined as B-type with which the inner profile of orbiting scroll and the outer profile of fixed scroll can be formed. The scroll compression chambers corresponding to the pitch lines of A-type and that of B-type are defined as compression chambers of A-series and B-series, respectively. Then the general geometrical model of scroll compression chamber is set up. It can demonstrate the deforming, opening, and vanishing process of all scroll chambers. Copyright © 2010 by ASME.
Wu L.,Lanzhou University of Technology
Journal of the Electrochemical Society | Year: 2012
In this paper, wafer topographys effects on the contact pressure distribution during CMP are investigated and calculated based on 3D solid-solid contact model. In the model, wafer is treated as a rigid punch and pad as a half-elastic space. The height variation on the wafer surface is assumed as a function of two dimensions and is described by TG(x, y). Based on the linear elasticity theory, a formula of calculating the contact pressure distribution between the wafer and the pad is deduced in an analytical way. The performance of CMP system is shown to be a linear system. The formula shows that when the wafer topography is expressed as 2-D Fourier expansions, the contact pressure between the wafer and the pad can be represented as a linear combination of e-i(ω αx+ω βy) with the same frequencies and different amplitudes. The 3D magnitude spectra of the CMP system are obtained exactly by the formula. The evolution of the wafer topography consisting of two square wave features with different densities is simulated and compared with experimental data. The formula proposed in the paper will help to specify the polishing parameters during CMP. It also provides a novel method to calculate contact pressure distribution when a rigid body with complicated 3D topography contacts with flat flexible base completely. © 2012 The Electrochemical Society.