Can we prevent the gaming of ramp constraints?

Some electric power markets allow bidders to specify constraints on ramp rates for increasing or decreasing power production. We show in a small example that a bidder could use an overly restrictive constraint to increase profits, and explore the cause by visualizing the feasible region from the linear program corresponding to the power auction. We propose three penalty approaches to discourage bidders from such a tactic: two based on the duality theory of linear programming (LP) and the other based on social cost differences caused by ramp constraints. We evaluate the approaches using a simplified scaled model of the California power system, with actual 2001 California demand data.     

城市视角下的建筑坡道设计——以库哈斯为例

建筑坡道是解决垂直联系的交通空间,其设计对空间流线的组织起着十分重要的作用,并直接影响到使用者的空间感受。近年来,伴随着相关空间理论的发展,建筑坡道设计在塑造公共空间和联系城市空间上的作用日益凸显。该文结合"倾斜平面"和"中介空间"理论,以库哈斯为例阐述了城市视角下的建筑坡道设计。文章对库哈斯所设计的康索尔艺术中心、朱苏大学图书馆方案和乌德勒支教育馆进行了详解,三个建筑采用了三种不同的坡道设计策略,表达对不同城市问题的思考。     

Dynamic economic dispatch using artificial immune system for units with valve-point effect

Dynamic economic dispatch (DED) is an important dynamic problem in power system operation and control. The objective of the problem is to schedule power generation for the online units over a time horizon, satisfying the unit and ramp-rate constraints. In this paper, clonal selection based artificial immune system (AIS) algorithm is used to solve the dynamic economic dispatch problem for generating units with valve-point effect. The feasibility of the proposed method is validated with ten and five unit test systems for a period of 24 h. Results obtained with the proposed approach are compared with other techniques in the literature. The results obtained substantiate the robustness and proficiency of the proposed methodology over other existing techniques in terms of solution quality and computational efficiency.     

An ADC BIST with on-chip ramp generator

This work presents built-in self-test (BIST) techniques for the production testing of mixed signal circuits. The special test strategy for the typical mixed-signal component analog-to-digital converter (ADC) is discussed. The traditional test for such mixed-signal components can be completed through a DSP-based mixed-signal tester with an arbitrary waveform generator and a signal digitizer, but such a test is very costly and time consuming. Hence, a BIST strategy based on an on chip ramp generator (OCRG) is proposed in this work for testing ADC. This BIST method has an advantage testing ADC without DAC to overcome area overhead. This BIST method realizes the test controller, test pattern generation and output response analyser at the aspect of the on-chip circuitry. The demonstration of the proposed BIST is given through various simulation results in the last parts of this work.     

地震相在塔里木盆地古城地区碳酸盐岩台地演化及特征分析中的应用

古城地区钻井资料欠缺。通过单井相分析、单井相标定地震相、地震相分析,研究了古城台地演化特征。台地的发育经历了缓坡-弱镶边台地-镶边台地的发育过程。从早寒武世到早中奥陶世,斜坡带的宽度依次变窄,台地边缘带的宽度呈变宽的趋势,并在地震反射外形上从初期的无明显外形特征演变到早中奥陶世的丘状外形。到中奥陶世末期,台地边缘演化到较高能型的台地边缘,但未到高能型的台地边缘。平面地震相分析表明,台地在演化过程中各相带的展布具有不规则性。研究区台地的演化属渐变过程,与塔中台地的类型形成鲜明对比。台地的沉积类型早期以相对静水沉积为主,逐渐发展到相对高能沉积。台地边缘碳酸盐岩建隆以灰泥丘为主,颗粒灰岩胶结良好,骨架礁体不发育。     

裂缝性碳酸盐岩气藏相控条件下测井裂缝解释——以土库曼斯坦阿姆河右岸为例

土库曼斯坦阿姆河右岸为盐下中上侏罗统低能缓坡礁滩型碳酸盐岩储层,储层基质物性差,裂缝发育。单井产能与裂缝发育程度密切相关,准确评价裂缝发育程度是产能建设过程中极为重要的一环。通过对研究区不同倾角裂缝有效性进行分析,认为高角度裂缝的有效性较高,对生产起主导作用;根据岩心观察统计、成像测井裂缝解释及常规测井响应特征分析,认为裂缝发育程度与双侧向幅度差大小及总孔隙度与声波孔隙度之差呈线性正相关,但不同岩相裂缝发育程度的测井响应特征存在差异;通过开展从单变量到相控_单变量的常规测井裂缝评价研究,最终采用“相控”多元线性回归方法,实现了不同岩相裂缝密度定量解释,形成了相控_多变量裂缝发育程度定量解释方法。岩心资料、测试资料及井漏情况表明解释结果较为可靠,可应用于相似类型储层裂缝发育程度常规测井定量评价。     

公路施工放样中若干问题探讨

随着社会经济的大力发展,交通设施也不断的完善,对公路的需求也越来越大,近几年,我国大力修建公路,而公路施工放样在公路建设中至关重要。而在公路施工放样过程中经常会碰到一些通视条件与精度问题,从而影响工程进度。本文介绍了在公路施工中,偏角法放样在处理一些视线障碍问题时的可取之处,全站仪极坐标放样法在匝道中线定位中的应用以及对其进行精度分析。     

Natural convection in attics subject to instantaneous and ramp cooling boundary conditions

A fundamental study of the fluid dynamics inside an attic shaped triangular enclosure with cold upper walls and adiabatic horizontal bottom wall is reported in this study. The transient behaviour of the attic fluid which is relevant to our daily life is examined based on a scaling analysis. The transient phenomenon begins with the instantaneous cooling and the cooling with linear decreases of temperature up to some specific time (ramp time) and then maintain constant of the upper sloped walls. It is shown that both inclined walls develop a thermal boundary layer whose thicknesses increase towards steady state or quasi-steady values. A proper identification of the time scales, the velocity and the thickness relevant to the flow that develops inside the cavity makes it possible to predict theoretically the basic flow features that will survive once the thermal flow in the enclosure reaches a steady state. A time scale for the cooling-down of the whole cavity together with the heat transfer scales through the inclined walls has also been obtained through scaling analysis. All scales are verified by the numerical simulations.     

Langjährige Erfahrungen des Tragverhaltens von Bewehrte‐Erde‐Brückenwiderlagern

Das Bauverfahren „Bewehrte Erde“ wurde nach der Einführung in den frühen 60‐er Jahren des letzten Jahrhunderts zum Bau von zahlreichen Stützwänden und Brückenwiderlagern angewandt. Der Beginn der Erforschung des Tragverhaltens von Bewehrte‐Erde‐Brückenwiderlagern liegt mehr als 40 Jahre zurück. Seitdem sind durch Modellversuche, Messungen an Test‐ und reellen Bauwerken zahlreiche Verbesserungen und Optimierungen am entwickelten Berechnungsverfahren erreicht worden. Dieser Beitrag soll Bauherren, Ingenieurbüros und bauausführenden Firmen für den Anwendungsfall „Brückenwiderlager“ im Bauverfahren „Bewehrte Erde“ sensibilisieren und daran erinnern, dass, bedingt durch seine zahlreichen technischen und ökonomischen Vorteile, dieses Bauverfahren bei unseren europäischen Nachbarn sowie weltweit für Brückenwiderlager nahezu als Standardbauweise gilt. A long experience in structural behaviour of Reinforced Earth for the application of bridge abutments. Since Reinforced Earth was invented in the early 60s of the last century, many retaining walls and bridge abutments had been erected using this technique. The main research of the load bearing behaviour of reinforced earth bridge abutments started more than 40 year ago. Since that many improvements by exploring scale models, measurements on test and real structures had been executed. This article shall remind clients, contractors and engineers the Reinforced Earth is combining technical and economical advantages for the application of bridge abutments.     

永磁同步电机的双闭环调速系统设计

永磁同步电机因其优越的性能近年来得到了广泛应用。针对双闭环控制器参数整定困难所导致的控制效果不佳的问题,文中提出了基于极点配置和Ramp函数的改进型双闭环PI控制器。从永磁同步电机矢量控制算法的角度出发,建立了速度、电流双闭环解耦控制的系统模型,并在此模型下论述了速度环、电流环控制器的设计方法,给出改进后双闭环控制器参数的计算结果。对所研究方法分别进行了计算机仿真和实际试验,结果表明优化后的系统减小了系统过冲,缩短了稳定时间,提高了系统动态响应,具有良好的工程意义。