On Capacity and Delay of Multi-channel Wireless Networks with Infrastructure Support

In this paper, we propose a novel multi-channel network with infrastructure support, called an MC-IS network, which has not been studied in the literature. To the best of our knowledge, we are the first to study such an MC-IS network. Our proposed MC-IS network has a number of advantages over three existing conventional networks, namely a single-channel wireless ad hoc network (called an SC-AH network), a multi-channel wireless ad hoc network (called an MC-AH network) and a single-channel network with infrastructure support (called an SC-IS network). In particular, the network capacity of our proposed MC-IS network is $\sqrt{n \log n}$ times higher than that of an SC-AH network and an MC-AH network and the same as that of an SC-IS network, where $n$ is the number of nodes in the network. The average delay of our MC-IS network is $\sqrt{\log n/n}$ times lower than that of an SC-AH network and an MC-AH network, and $\min\{C_I,m\}$ times lower than the average delay of an SC-IS network, where $C_I$ and $m$ denote the number of channels dedicated for infrastructure communications and the number of interfaces mounted at each infrastructure node, respectively. Our analysis on an MC-IS network equipped with omni-directional antennas only has been extended to an MC-IS network equipped with directional antennas only, which are named as an MC-IS-DA network. We show that an MC-IS-DA network has an even lower delay of $\frac{c}{\lfloor \frac{2\pi}{\theta}\rfloor \cdot C_I}$ compared with an SC-IS network and our MC-IS network. For example, when $C_I=12$ and $\theta=\frac{\pi}{12}$, an MC-IS-DA network can further reduce the delay by 24 times lower that of an MC-IS network and reduce the delay by 288 times lower than that of an SC-IS network.Comment: accepted, IEEE Transactions on Vehicular Technology, 201

Liver Cancer Treatment by Chinese Medicines and their Active Compounds

Recent studies have indicated that traditional Chinese medicines (CMs) and their active compounds play an important role in liver cancer treatment by preventing tumor formation, inhibiting tumor growth, metastasis and recurrence as well as improving the quality of life and reducing side effects of radiotherapy and chemotherapy. Mechanism studies have proved the advantage of multicomponent, multitarget and multipathway combinational regulation by CMs in liver cancer treatment. This chapter emphatically introduces the molecular mechanisms underlying liver cancer treatment by CMs. In addition, we also put forward discussion on existing obstacles and prospect of the future development on liver cancer treatment using CMs, in terms of providing a comprehensive understanding of action of CMs in liver cancer treatment

The Role of Cell Autophagy in Cancer and Its Application in Drug Discovery

Autophagy is a vital basic phenomenon that widely exists in eukaryotic cells. As one type of programmed cell death, autophagy has gained much more attention in the past few years. Recent studies suggest that the alterations in autophagy are associated with the genesis and development of cancers. It can affect cell apoptosis, angiogenesis, and treatment of tumor. Others’ and our studies have found that some herbal medicines can induce autophagic cell death in cancer cell models. As herbal medicines are very important recourses for drug discovery and lead compounds of anticancer drugs, we have summarized the role of autophagy in inhibitive effect of natural products in cancer cell growth and metastasis. Finally, we present summary and critical comments on problems in current autophagy study and its future prospect

Porphyrin‐Based Organophotocatalysts

The planar geometric structure and the rich absorption feature endow porphyrins with interesting optoelectronic properties and also make it promising building blocks for supramolecular assembly. Recent advances in the photocatalytic applications of porphyrins, including homogeneous, heterogeneous photocatalysis, and photoelectrochemical solar cells are highlighted. Porphyrin photocatalysts are involved in the form of molecules, supported molecules, nanostructures, and thin film. Related rational design strategies are provided for each form with an aim to enhance the light conversion efficiency. Finally, the ongoing directions and challenges for the future development of porphyrin semiconductors in high‐quality optoelectronic devices are also proposed

Neural learning enhanced variable admittance control for human-robot collaboration

© 2013 IEEE. In this paper, we propose a novel strategy for human-robot impedance mapping to realize an effective execution of human-robot collaboration. The endpoint stiffness of the human arm impedance is estimated according to the configurations of the human arm and the muscle activation levels of the upper arm. Inspired by the human adaptability in collaboration, a smooth stiffness mapping between the human arm endpoint and the robot arm joint is developed to inherit the human arm characteristics. The estimation of stiffness term is generalized to full impedance by additionally considering the damping and mass terms. Once the human arm impedance estimation is completed, a Linear Quadratic Regulator is employed for the calculation of the corresponding robot arm admittance model to match the estimated impedance parameters of the human arm. Under the variable admittance control, robot arm is governed to be complaint to the human arm impedance and the interaction force exerted by the human arm endpoint, thus the relatively optimal collaboration can be achieved. The radial basis function neural network is employed to compensate for the unknown dynamics to guarantee the performance of the controller. Comparative experiments have been conducted to verify the validity of the proposed technique

High photo-excited carrier multiplication by charged InAs dots in AlAs/GaAs/AlAs resonant tunneling diode

We present an approach for the highly sensitive photon detection based on the quantum dots (QDs) operating at temperature of 77K. The detection structure is based on an AlAs/GaAs/AlAs double barrier resonant tunneling diode combined with a layer of self-assembled InAs QDs (QD-RTD). A photon rate of 115 photons per second had induced 10nA photocurrent in this structure, corresponding to the photo-excited carrier multiplication factor of 10^7. This high multiplication factor is achieved by the quantum dot induced memory effect and the resonant tunneling tuning effect of QD-RTD structure.Comment: 10 pages,5 figures. Submitted to Applied Physics Letter

Mathematical modelling for multiproduct EPQ problem featuring delayed differentiation, expedited rate, and scrap

The client requirements of present-day markets emphasize product quality, variety, and rapid response. To gain competitive advantages in marketplaces and meet customer needs, manufacturers today seek the most economical and fastest fabrication schemes and strategies to produce their various goods, especially when commonality exists within these multiple end products. Inspired by the above viewpoints, this study uses a mathematical modelling approach for solving a multiproduct economic production quantity (EPQ) problem featuring scrap, delayed differentiation, and expedited rate on the fabrication of the common part. We build a two-stage multiproduct fabrication scheme. Stage one uses an accelerated rate to produce all necessary common parts for multi-item to shorten its uptime, while stage two fabricates finished products sequentially using a rotation cycle rule. Inevitable random scraps produced in both stages are identified and removed to achieve the anticipated quality. We determined the optimal cost-minimization operating cycle length and used a numerical example to show our model’s capability and to explore collective and individual impacts of scrap, expedited-rate, and postponement strategies on various performances of the studied problem (such as uptime of common part, utilization, rotation cycle time, total system cost, and individual cost contributor, etc.) Our model can offer an optimization solution and in-depth managerial insights for fabrication and operations planning in a wide variety of present-day industries, such as automotive, household goods, clothing, etc