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131.
A predictive model for the reactor inorganic suspended solids concentration in activated sludge systems 总被引:1,自引:0,他引:1
A simple predictive model for the activated sludge reactor inorganic suspended solids (ISS) concentration (excluding that from chemical precipitant dosing) is presented. It is based on the accumulation of influent ISS in the reactor and an ordinary heterotrophic organism (OHO) ISS content (fiOHO) of 0.15 mg ISS/mg OHO organic (volatile) suspended solids (VSS) and a variable phosphate accumulating organism (PAO) ISS content (fiPAO) proportional to their P content (fXBGP). Organism ISS content is conceptualized as the uptake of dissolved inorganic solids by active organisms, which when dried in the total suspended solids (TSS) test procedure, precipitate and manifest as ISS. The model is validated with data from 22 investigations conducted over the past 15 years on 30 aerobic and anoxic-aerobic nitrification-denitrification (ND) systems and 18 anaerobic-anoxic-aerobic ND biological excess P removal (BEPR) systems variously fed artificial and real wastewater, and operated from 3 to 20 days sludge age. The predicted reactor VSS/TSS ratio reflects the observed relative sensitivity to sludge age, which is low, and to BEPR, which is high. To use the model for design, two parameters need to be known: (1) the influent ISS concentration, which is not commonly measured in wastewater characterization analyses and (2) the P content of PAOs (fXBGP), which can vary considerably depending on the extent of anoxic P uptake BEPR that takes place in the system. Some guidance on the measurement of influent ISS concentration and selection of the PAO P content to calculate the mixed liquor VSS/TSS ratio for design is given. 相似文献
132.
In this paper, a new method of multivariable predictive control is presented. The main advantage of a predictive approach is that multivariable plants with time delays can be easily handled. The proposed control algorithm also introduces a compact and simple design in the case of higher-order and nonminimal phase plants, but it is limited to open-loop stable plants. The algorithm of the proposed multivariable predictive control is developed, designed, and implemented on an air-conditioned system. The stability of the proposed control law is discussed. 相似文献
133.
134.
烧结终点提前预报对于稳定终点,进而提高烧结矿强度和产量、降低能耗有重要意义.为解决烧结过程大滞后环节和烧结终点难以测量的困难,文章介绍了烧结终点的软测量方法;提出了一个新的预报参数——风箱废气温度曲线拐点;将BP神经网络应用于烧结终点的预报,实现了准确地预报烧结终点的状态和生产操作指导. 相似文献
135.
针时常规神经网络和模糊神经网络的不足,介绍了一种具有快速算法的补偿模糊神经网络,并根据电火花加工的工艺特点及其复杂性,建立了基于补偿模糊神经网络的电火花加工工艺效果预测模型,可实现指定加工条件下的工艺效果预测.仿真结果显示了其良好的预测精度,其性能优于常规模糊神经网络. 相似文献
136.
137.
Control of dynamic keyhole welding process 总被引:1,自引:0,他引:1
Weld joint penetration control is a basic research topic in the welding research community. The authors propose using an innovative plasma arc welding process referred to as the quasi-keyhole process to achieve less application-dependent weld joint penetration sensing and control. To control the quasi-keyhole process, the peak current and keyhole sustaining current are selected as the control variables to maintain the keyhole establishment and sustaining periods at desired values. The dynamic quasi-keyhole process is approximated by a linear model with interval parameters. A control algorithm has been developed for the multivariable interval quasi-keyhole process based on a predictive control algorithm for interval SISO models. Experiments have been conducted to test the effectiveness of the control system developed. 相似文献
138.
Multiple access control (MAC) protocols play a significant role in wireless LANs. The IEEE 802.11 MAC protocol specifies two
coordination functions that are Distributed Coordination Function (DCF) and Point Coordination Function (PCF). While both
DCF and PCF are available in a wireless cell, we propose a novel access mechanism called Adaptive Coordination Function (ACF)
to support various classes of traffic. The ACF superframe comprises two periods, one TDMA period designed for real-time traffic
and followed by an adaptive period which adaptively employs DCF or PCF to support non-real-time traffic. In this paper, we
apply the theory of M/G/1 queues to analyze the performance of adaptive period in terms of queuing delay, end-to-end delay,
and saturation throughput. With our analytic model, DCF or PCF can be invoked appropriately according to the number of stations,
packet arrival rate, packet payload size, and effective channel bit rate. Analytical results are derived for an extensive
throughput and delay performance evaluation of both DCF and PCF. 相似文献
139.
用VHDL语言设计了100BASE-T4快速以太网HUB中数据转发器电路;分析了基于CSMA/CD协议的T4快速以太网HUB物理子层数据编码和传输机制;硬件结构包括端口控制电路、仲裁电路、时钟多路选择器电路、FIFO电路、核心控制电路、标志生成输出多路选择器电路;用MAX+PLUSⅡ软件进行了仿真调试和器件下载测试,结果表明该电路系统实现了数据转发目的并且满足CSMA/CD物理子层协议的要求。 相似文献
140.
Wireless LAN technologies such as IEEE 802.11a and 802.11b support high bandwidth and multi-rate data transmission to match
the channel condition (i.e., signal to noise ratio). While some wireless packet fair queuing algorithms to achieve the per-flow
throughput fairness have been proposed, they are not appropriate for guaranteeing QoS in multi-rate wireless LAN environments.
We propose a wireless packet scheduling algorithm that uses the multi-state (multi-rate) wireless channel model and performs
packet scheduling by taking into account the channel usage time of each flow. The proposed algorithm aims at per-flow protection
by providing equal channel usage time for each flow. To achieve the per-flow protection, we propose a temporally fair scheduling
algorithm called Contention-Aware Temporally fair Scheduling (CATS) which provides equal channel usage time for each flow.
Channel usage time is defined as the sum of the packet transmission time and the contention overhead time due to the CSMA/CA
mechanism. The CATS algorithm provides per-flow protection in wireless LAN environments where the channel qualities of mobile
stations are dynamic over time, and where the packet sizes are application-dependent. We also extend CATS to Decentralized-CATS
(D-CATS) to provide per-flow protection in the uplink transmission. Using an NS-2 simulation, we evaluate the fairness property
of both CATS and D-CATS in various scenarios. Simulation results show that the throughput of mobile stations with stable link
conditions is not degraded by the mobility (or link instability) of other stations or by packet size variations. D-CATS also
shows less delay and less delay jitter than FIFO. In addition, since D-CATS can coordinate the number of contending mobile
stations, the overall throughput is not degraded as the number of mobile stations increases.
This work was supported in part by the Brain Korea 21 project of Ministry of Education and in part by the National Research
Laboratory project of Ministry of Science and Technology, 2004, Korea. 相似文献