Research on Multifunctional Integrated Internet Platforms

Throughout the development of China’s Internet industry for more than 20 years, we can tease out three stages that can represent the trend of the times: the first stage can be called the Portal Era with the entire Internet industry dominated by portal websites. However, with several major portals ’transitions after being unable to maintain effective operation of their profit model, the Portal Era came to an end. The second stage we call Social Network Era , represented by Sina Mircroblog and WeChat. The former had successful transitions after several ups and downs and the latter is trending and promising. Also vigorously developing are various social websites and mobile apps. In the midst of the laughter of those entrepreneurs, the industry came to a third stage of development: The Era of E-business. These three stages did not appear one after another in chronological order. Social networks and e-business platforms in fact exist simultaneously with two groups of people hitting on different roads that lead to the same destination. Social networks and business platforms are now already inescapably intertwined with each other: social networks attract traffic for e-business platforms while e-business platforms provide profit in return. What is more, big Internet giants aim to create a theme park magnificently situated in the internet world to provide one-stop services like portal browsing, e-business, third party payment, social networking and entertainment. At the same time, social network leaders also gradually provided e-commerce .and the third party payment service without willing to pave way for others. Longer ago, with the smart phones sweeping the world, the mobile internet era approached quietly while online and offline businesses increasingly converged. Therefore, we have reasons to believe that the next important stage of Internet development will be named as the era of multi-functional integrated Internet platforms

High-Performance Packaging Technology for Wide Bandgap Semiconductor Modules

The properties of wide band gap (WBG) semiconductors are beneficial to power electronics applications ranging from consumer electronics and renewable energy to electric vehicles and high-power traction applications like high-speed trains. WBG devices, properly integrated, will allow power electronics systems to be smaller, lighter, operate at higher temperatures, and at higher frequencies than previous generations of Si-based systems. These will contribute to higher efficiency, and therefore, lower lifecycle costs and lower CO2 emissions. Over 20 years have been spent developing WBG materials, low-defect-density wafers, epitaxy, and device fabrication and processing technology. In power electronics applications, devices are normally packaged into large integrated modules with electrical, mechanical and thermal connection to the system and control circuit. The first generations of WBG device have used conventional or existing module designs to allow drop-in replacement of Si devices; this approach limits the potential benefit. To realize the full potential of WBG devices, especially the higher operating temperatures and faster switching frequency, a new generation of packaging design and technology concepts must be widely implemented

Status and Trend of Power Semiconductor Module Packaging for Electric Vehicles

Power semiconductor modules are the core components in power-train system of hybrid and electric vehicles (HEV/EV). With the global interests and efforts to popularize HEV/EV, automotive module has become one of the fast growing sectors of power semiconductor industry. However, the comprehensive requirements in power, frequency, efficiency, robustness, reliability, weight, volume, and cost of automotive module are stringent than industrial products due to extremely high standards of vehicle safety and harsh environment. The development of automotive power module is facing comprehensive challenges in designing of structure, material, and assembly technology. In this chapter, the status and trend of power semiconductor module packaging for HEV/EV are investigated. Firstly, the functionality of power electronics and module in HEV/EV power-train system, as well as the performance requirements by automotive industry, is addressed. A general overview of HEV/EV module design and manufacturing is discussed. Then, the typical state-of-the-art commercial and custom HEV/EV power modules are reviewed and evaluated. Lastly, the packaging trends of automotive module are investigated. The advanced assembly concept and technology are beneficial to thermal management, minimized parasitic parameters, enhancement of thermal and mechanical reliability, and the reduction of weight, volume, and cost

Development of a micro-indentation device for measuring the mechanical properties of soft materials

AbstractIndentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with high-precision to measure the mechanical properties of soft materials, where the shear modulus and Poisson's ratio of the materials can be obtained by analyzing the load–relaxation curve. We have validated the accuracy and stability of the system by comparing the measured mechanical properties of a polyethylene glycol sample with that obtained from a commercial instrument. The mechanical properties of another typical polydimethylsiloxane sample submerged in heptane are measured by using conical and spherical indenters, respectively. The measured values of shear modulus and Poisson's ratio are within a reasonable range

Bioprinting-Based High-Throughput Fabrication of Three-Dimensional MCF-7 Human Breast Cancer Cellular Spheroids

ABSTRACTCellular spheroids serving as three-dimensional (3D) in vitro tissue models have attracted increasing interest for pathological study and drug-screening applications. Various methods, including microwells in particular, have been developed for engineering cellular spheroids. However, these methods usually suffer from either destructive molding operations or cell loss and non-uniform cell distribution among the wells due to two-step molding and cell seeding. We have developed a facile method that utilizes cell-embedded hydrogel arrays as templates for concave well fabrication and in situ MCF-7 cellular spheroid formation on a chip. A custom-built bioprinting system was applied for the fabrication of sacrificial gelatin arrays and sequentially concave wells in a high-throughput, flexible, and controlled manner. The ability to achieve in situ cell seeding for cellular spheroid construction was demonstrated with the advantage of uniform cell seeding and the potential for programmed fabrication of tissue models on chips. The developed method holds great potential for applications in tissue engineering, regenerative medicine, and drug screening

Design of Moderator of a Compact Accelerator-driven Neutron Source for Coded Source Imaging

AbstractCoded source imaging (CSI) is a possible method to solve the contradiction between neutron flux and L/D ratio. Peking University neutron imaging facility (PKUNIFTY) is a RFQ accelerator based facility. The CSI experiments were carried out on PKUNFTY to test the benefits that this technique might bring. The CSI technique gets more restricts on the moderator, especially the neutron distribution in the inner collimator, where the coded mask sampling the source. The effect caused by the non-uniformity of neutron distribution on the mask plane was investigated. The slope type non-uniformity should less than 20% to keep the artifact in the reconstructed image insignificant. The PKUNIFTY moderator was modified according to the above limit. The preliminary experiments shown the moderator design for coded source imaging is acceptable

Lipid profiles in the cerebrospinal fluid of rats with 6-hydroxydopamine-induced lesions as a model of Parkinson’s disease

BackgroundParkinson’s disease (PD) is a progressive neurodegenerative disease with characteristic pathological abnormalities, including the loss of dopaminergic (DA) neurons, a dopamine-depleted striatum, and microglial activation. Lipid accumulation exhibits a close relationship with these pathologies in PD.MethodsHere, 6-hydroxydopamine (6-OHDA) was used to construct a rat model of PD, and the lipid profile in cerebrospinal fluid (CSF) obtained from model rats was analyzed using lipidomic approaches.ResultsEstablishment of this PD model was confirmed by apomorphine-induced rotation behaviors, loss of DA neurons, depletion of dopamine in the striatum, and microglial activation after 6-OHDA-induced lesion generation. Unsupervised and supervised methods were employed for lipid analysis. A total of 172 lipid species were identified in CSF and subsequently classified into 18 lipid families. Lipid families, including eicosanoids, triglyceride (TG), cholesterol ester (CE), and free fatty acid (FFA), and 11 lipid species exhibited significantly altered profiles 2 weeks after 6-OHDA administration, and significant changes in eicosanoids, TG, CE, CAR, and three lipid species were noted 5 weeks after 6-OHDA administration. During the period of 6-OHDA-induced lesion formation, the lipid families and species showed concentration fluctuations related to the recovery of behavior and nigrostriatal abnormalities. Correlation analysis showed that the levels of eicosanoids, CE, TG families, and TG (16:0_20:0_18:1) exhibited positive relationships with apomorphine-induced rotation behaviors and negative relationships with tyrosine hydroxylase (TH) expression in the midbrain.ConclusionThese results revealed that non-progressive nigrostriatal degeneration induced by 6-OHDA promotes the expression of an impairment-related lipidomic signature in CSF, and the level of eicosanoids, CE, TG families, and TG (16:0_20:0_18:1) in CSF may reveal pathological changes in the midbrain after 6-OHDA insult

The role of Guanxi in green supply chain management in Asia's emerging economies: A conceptual framework

In recent decades, rapid industrial modernization and economic growth have brought substantial environmental problems such as air pollution, hazardous waste, and water pollution for the Asian Emerging Economies (AEE), in particular China, Taiwan, India, Malaysia, Indonesia, Thailand, and South Korea. These countries have started to adopt green supply chain management (GSCM) as a strategy to reduce the environmental impact. There are anecdotal evidences that the adoption of GSCM in this region is partly influenced by Guanxi – a cultural norm, which plays a significant role in relationship governance within supply chain activities among the AEE. Based on a systematic literature review, we develop a conceptual framework that characterizes the drivers and barriers for the adoption of GSCM practices, incorporating Guanxi as a moderator in the manufacturing sector of the AEE. The conceptual framework addresses the roles of two types of Guanxi in the adoption of GSCM: the relational Guanxi at individual level based on social exchange theory and the aggregated Guanxi at firm level derived from social capital theory. This recognition of Guanxi at two separate decision levels help companies better manage their relationships while they green their supply chains. Directions for future research and managerial implications are discussed accordingly

An Arbitrary-length and Multiplierless DCT Algorithm and Systolic Implementation

Abstract—Discrete Cosine transform (DCT) is an important tool in digital signal processing. In this paper, a novel algorithm to perform DCT multiplierlessly is proposed. First, by modular mapping and truncating Taylor series expansion, the DCT is expressed in the form of the product of the constants and discrete moments. Second, by performing appropriate bit operations and shift operations in binary system, the product can be transformed to some additions of integers. The proposed algorithm only involves integer additions and shifts because the discrete moments can be computed only by integer additions. An efficient and regular systolic array is designed to implement the proposed algorithm, and the complexity analysis is also given. Different to other fast Cosine transforms, our algorithm can deal with arbitrary length signals and get high precision. The approach is also applicable to multi-dimensional DCT and DCT inverses. Index Terms—discrete Cosine transform, moments, multiplierless, systolic array

Rapid Processing of Frames Refreshment with Viewpoint Movement Based on OpenGL for 3D Walkthrough System

How to refresh frames for 3D scenes efficiently with viewpoint movement is very important for a 3D walkthrough system. Detailed calculation process of movement position and destination position for the viewpoint in virtual 3D scenes is described, thus implementing controlling scenes through the application of an external device. Moreover, OpenGL Performer pfLOD node is utilized to process LOD (Level of Detail) display for improving scenes refreshment performance. With OpenGL's powerful interaction functions, 3D scenes are rendered with a fixed frame rate over 50 Hz. Then, details of MFC framework initialization and OpenGL initialization are given for Dalian nationalities university 3D walkthrough system. Running results of the software show the algorithm designed in this paper is feasible and effective and can meet requirements of real application