Efficient RC low-power bus encoding methods for crosstalk reduction

In on-chip buses, the RC crosstalk effect leads to serious problems, such as wire propagation delay and dynamic power dissipation. This paper presents two efficient bus-coding methods. The proposed methods simultaneously reduce more dynamic power dissipation and wire propagation delay than existing bus encoding methods. Our methods also reduce more total power consumption than other encoding methods. Simulation results show that the proposed method I reduces coupling activity by 26.7-38.2% and switching activity by 3.7%-7% on 8-bit to 32-bit data buses, respectively. The proposed method II reduces coupling activity by 27.5-39.1% and switching activity by 5.3-9% on 8-bit to 32-bit data buses, respectively. Both the proposed methods reduce dynamic power by 23.9-35.3% on 8-bit to 32-bit data buses and total propagation delay by up to 30.7-44.6% on 32-bit data buses, and eliminate the Type-4 coupling. Our methods also reduce total power consumption by 23.6-33.9%, 23.9-34.3%, and 24.1-34.6% on 8-bit to 32-bit data buses with the 0.18, 0.13, and 0.09 μm technologies, respectively.     

Enhancement of hydrogen reaction in a micro-channel by catalyst segmentation

The paper addresses the combustion characteristics of multi-segment catalysts in a micro-reactor by numerical simulation with detailed heterogeneous and homogeneous chemistries. The effect of multi-segment catalyst is delineated in terms of different catalyst dispositions, different flow conditions and different reactor properties. With a fixed total catalyst length (1 cm), multi-segment catalyst reveals better performance than single catalyst. The space between catalyst segments reduces the inhibition of homogeneous reactions by catalyst and promotes homogeneous reactions in this region since the neighboring catalysts help to maintain a high wall temperature. Therefore, homogeneous combustion can shift upstream with the multi-segment catalyst. The results of different catalyst dispositions show that more catalyst segments has better performance but the catalyst space distance has no obvious effects due to the fast reaction rate of hydrogen. For different flow conditions, the results indicate multi-segment catalyst disposition has better conversion ratio even though there is no homogeneous combustion in the fluid region for fuel-lean condition. The results for different inlet velocities show that multi-segment catalyst has no obvious benefit on lower inlet velocity. However, it can extend the blowout velocity. Finally different reactor dimension and wall material are simulated. Although heterogeneous reactions strengthen in small channel, multi-segment catalyst still has obvious benefit. The results of different wall thermal conductivity do not have obvious difference for multi-segment catalyst. These results can be used in the design of a catalytic micro-reactor for hydrogen/air reactions.     

Dengue Nonstructural Protein 1 Maintains Autophagy through Retarding Caspase-Mediated Cleavage of Beclin-1

Dengue virus (DENV) infection is a significant public health threat in tropical and subtropical regions; however, there is no specific antiviral drug. Accumulated studies have revealed that DENV infection induces several cellular responses, including autophagy and apoptosis. The crosstalk between autophagy and apoptosis is associated with the interactions among components of these two pathways, such as apoptotic caspase-mediated cleavage of autophagy-related proteins. Here, we show that DENV-induced autophagy inhibits early cell apoptosis and hence enhances DENV replication. Later, the apoptotic activities are elevated to suppress autophagy through cleavage of Beclin-1, an essential autophagy-related protein. Inhibition of cleavage of Beclin-1 by a pan-caspase inhibitor, Z-VAD, increases both autophagy and viral replication. Regarding the mechanism, we further found that DENV nonstructural protein 1 (NS1) is able to interact with Beclin-1 during DENV infection. The interaction between Beclin-1 and NS1 attenuates Beclin-1 cleavage and facilitates autophagy to prevent cell apoptosis. Our study suggests a novel mechanism whereby NS1 preserves Beclin-1 for maintaining autophagy to antagonize early cell apoptosis; however, elevated caspases trigger apoptosis by degrading Beclin-1 in the late stage of infection. These findings suggest implications for anti-DENV drug design.     

A projection approach to stability analysis and design of fuzzy systems

The stability analysis and design of the systems, described in Takagi-Sugeno's (TS) fuzzy model, are discussed in this correspondence. Based on the alternating projection method, the stability issue can be extended to a prescribed stability region. And the projection algorithm is proposed for assuring the desired stability. By involving the controller, we further introduce the design issues for the closed-loop system. Some numerical examples are given to demonstrate the validity and feasibility.     

Changes of organo-montmorillonite by ball-milling in water and kerosene

An experimental study has been conducted to evaluate the changes of montmorillonite under various conditions, such as different solvent (water and kerosene), intercalation by mixing and stirred ball-milling. The montmorillonite was prepared from bentonite mined in Taitung, Eastern Taiwan. The final product of exfoliated organic montmorillonite was obtained by treatment in water and kerosene systems. The XRD results show that stirred ball-milling is an effective physical operation for breaking down the size of the clay particles and facilitating the intercalation of ammonium ions. The optimum duration for stirred ball-milling was 6 h in both systems. In water the basal spacing increased gradually from 1.27 nm to 2.41 nm with dodecylammonium ions in the case of mixing and from 3.19 to 4.55 nm for dodecylammonium and hexadecylammonium ions during 2 h of ball-milling, respectively.     

A Mini-Invasive Long-Term Bladder Urine Pressure Measurement ASIC and System

A mini-invasive system for long-term bladder urine pressure measurement system is presented. Not only is the design cost reduced, but also the reliability is enhanced by using a 1-atm canceling sensing instrumentation amplifier (IA). Because the urine pressure inside the bladder does not vary drastically, both the sleeping and working modes are required in order to save the battery power for long-term observation. The IA amplifies the signal sensed by the pressure sensor, which is then fed into the following analog-to-digital converter. Owing to the intrinsic 1-atm pressure existing inside the bladder, the IA must be able to cancel such a pressure from the signal picked up by the pressure sensor to keep the required linearity and the resolution for pressure measurement of the bladder urine. The pressure range of the proposed system is found out to be 14.7~19.7 Psi, which covers the range of all of the known unusual bladder syndromes or complications.     

A predictive handover scheme to improve service quality in the IEEE 802.21 network

The Media Independent Handover (MIH) standard defined in the IEEE 802.21 specification supports vertical handovers across heterogeneous networks. A cross-layer scheduling scheme is proposed to exploit Link Going Down information from MIH to predict handover requirements, and then improve the performance of Quality of Service (QoS) enabled transport services given the limited radio spectrum available for handovers in a heterogeneous network environment. According to simulation results, the proposed scheme can effectively increase the effective range of QoS sensitive services at the cell border while executing the handover procedure.     

Super-Imposed Training Scheme for Timing and Frequency Synchronization in OFDM Systems

In this paper, a super-imposed scheme for timing and frequency synchronization is proposed for orthogonal frequency division multiplexing (OFDM) systems. The proposed architecture includes a pre-defined pseudo-noise (PN) sequence, which is added to both the OFDM symbol and the cyclic prefix (CP) in time domain. In contrast to existing synchronization schemes, the proposed architecture has the advantage of better bandwidth utilization since it does not require extra pilot symbols. The peak-to-average power ratio (PAPR) is also significantly decreased. Both the timing and frequency offset estimators are derived using the maximum likelihood (ML) criterion. Efficiencies of the estimators are analyzed mathematically in AWGN channels. Simulation experiments are also conducted in frequency selective fading channels. Moreover, the optimal power allocation factor of the PN sequence is determined by minimizing the bit error rate using simulation experiments     

Macrodiversity technique for improvement in BER in wireless systems

The authors analyse a novel macrodiversity scheme, the multiply-detected macrodiversity (MDM) scheme, which relies on post-detection combining, as opposed to the traditional macrodiversity techniques, which are selection-based. The average fraction of the cell area is evaluated with an improved bit error rate (BER) performance, average BER improvement, and improvement in the average outage probability, relative to three other selection-based macrodiversity schemes. As a point of reference, the average improvement in BER is always at least one order of magnitude throughout at least 25%, of the cell area, when the probability of the co-channel interferer's presence is not >70%     

The multiply-detected macrodiversity scheme for wireless cellularsystems

The multiply-detected macrodiversity (MDM) scheme is proposed for wireless cellular systems. As opposed to the traditional macrodiversity schemes, in which at any time a signal from only one base station is selected, in the MDM scheme there is no selection, but all the received signals are detected, and a maximum-likelihood decision algorithm is employed to maximize the probability of correct decision. We study the performance of the MDM scheme and compare it with the performance of the traditional selection-based macrodiversity schemes. Depending on the propagation parameters, our results show that through the use of the MDM scheme, significant improvement in the bit-error rate (BER) can be achieved. For instance, if the outage probability is defined as BER above 10^-4 the outage is eliminated at least 45% of the time as compared with signal-to-interference (S/I) diversity, for a propagation attenuation exponent of 4.0 and shadowing standard deviation of 4.0 dB. Furthermore, as compared with the (S/I) diversity, the MDM scheme reduces, on the average, the BER at least two orders of magnitude throughout more than 60% of the cell area for a propagation attenuation exponent of 3.5, shadowing standard deviation of 4.0 dB and system loading of less than 50%