This study proposes a multiple-output differential-input operational transconductance amplifier-C (MODI OTA-C) filter with an impedance scaler to detect cardiac activity. A ladder-type fifth-orderButterworth low-pass filter with a large time constant and low noise is implemented to reduce coefficient sensitivity and address signal distortion. Moreover, linearized MODI OTA structures with reduced transconductance and impedance scaler circuits for noise reduction are used to achieve a wide dynamic range (DR). The OTA-based circuit is operated in the subthreshold region at a supply voltage of 1 V to reduce the power consumption of the wearable device in long-term use. Experimental results of the filter with a bandwidth of 250 Hz reveal that DR is 57.6 dB, and the harmonic distortion components are below -59 dB. The power consumption of the filter, which is fabricated through a TSMC 0.18 µm CMOS process, is lower than 390 nW, and the active area is 0.135 mm2.

In a shared buffer packet switch, a good buffer management scheme is needed to reduce the overall packet loss probability and improve the fairness between different users. In this paper, a novel buffer control scheme called partial sharing and partial partitioning (PSPP) is proposed. The PSPP is an adaptive scheme that can be dynamically adjusted to the changing traffic conditions while simple to implement. The key idea of the PSPP is that part of the buffer space, proportional to the number of inactive output ports, is reserved for sharing between inactive output ports. This portion of buffer is called PS buffer. The residual buffer space, called PP buffer, is partitioned and distributed to active output ports equally. From the analysis results, we only need to reserve a small amount of PS buffer space to get good performance for the entire system. Computer simulation shows the PSPP control is very robust and very close to the performance of pushout (PO) buffer management scheme which is a scheme considered as optimal in terms of fairness and total loss ratio while too complicated for implementation.

Grid computing is a state-of-the-art parallel computing technology which enables worldwide computers to dynamically share their computing powers and resource to each other. The grid takes advantage of Internet as a universal communication platform to carry messages. Basically, Internet doesn't guarantee loss-free and ordered transmission, hence, the grid should keep the cause and effect of events by itself to ensure the correct ordering of command invocations at the remote hosts. The ordering issue arises when the messages travel across the networks with unpredictable delay. Recent research has studied the security and resource control issues, but failed to address the requirements of transport layer on the grid communication platform. In this paper, we propose the Causal Ordered Grid (COG) architecture and implement it to study the transport performance issues when the grid is built over worldwide networks. The COG provides a novel service model to the applications with time-sensitive and causal-ordered transportation. From our experiments, the design of the grid middleware should use a causal-ordered, time-sensitive transportation rather than TCP. Our research will be beneficial to the improvement of the grid computing and can provide wealthy empirical results for the designer.