Local distributions of electricity demand

A simple model for how electricity use might be distributed over space is developed and solved. The model depends on a simple characterization of “heat islands”, and considers summer cooling use in particular. Various technological changes to allow for electric grid use of renewable energy and other technologies, such as energy efficiency and hydrogen or electric vehicles, change the outcome of this model, and produce a “saddle”, not necessarily a “duck curve”. Inequality in income and wealth drives these results, and policies to ameliorate or remove these effects will have to be and be seen as fair to those of various income levels and locations.     

Decentralized control: Status and outlook

This paper reviews state of the art in the area of decentralized networked control systems with an emphasis on event-triggered approach. The models or agents with the dynamics of linear continuous-time time-invariant state-space systems are considered. They serve for the framework for network phenomena within two basic structures. The I/O-oriented systems as well as the interaction-oriented systems with disjoint subsystems are distinguished. The focus is laid on the presentation of recent decentralized control design and co-design methods which offer effective tools to overcome specific difficulties caused mainly by network imperfections. Such side-effects include communication constraints, variable sampling, time-varying transmission delays, packet dropouts, and quantizations. Decentralized time-triggered methods are briefly discussed. The review is deals mainly with decentralized event-triggered methods. Particularly, the stabilizing controller–observer event-based controller design as well as the decentralized state controller co-design are presented within the I/O-oriented structures of large scale complex systems. The sampling instants depend in this case only on a local information offered by the local feedback loops. Minimum sampling time conditions are discussed. Special attention is focused on interaction-oriented system architecture. Model-based approach combined with event-based state feedback controller design is presented, where the event thresholds are fully decentralized. Finally, several selected open decentralized control problems are briefly offered as recent research challenges.     

Energy innovations through blockchain: Challenges,opportunities, and the road ahead

As a secure distributed ledger, blockchain has attracted a great deal of attention over the past decade. The power sector is not an exception to this phenomenon and industry leaders are looking into different ways to create value through this technology. Blockchain is a powerful enabling technology for decentralization of the energy systems of the future. Although this technology can be applied to a wide spectrum of applications in the power sector, many challenges and limitations are still needed to be addressed before its full implementation into grid operations. This paper presents energy innovations through the blockchain technology and addresses the barriers that preclude the power sector from large-scale, full-scope adoption of this technology. The emerging blockchain trends in near future will be further discussed and its potential in facilitating a secure, decentralized energy trading platforms will be investigated in this paper.     

Optimal memoryless control in Gaussian noise: A simple counterexample

In this paper, we investigate control strategies for a scalar, one-step delay system in discrete-time, i.e., the state of the system is the input delayed by one time unit. In contrast with classical approaches, here the control action must be a memoryless function of the output of the plant, which comprises the current state corrupted by measurement noise. We adopt a first order state-space representation for the delay system, where the initial state is a Gaussian random variable. In addition, we assume that the measurement noise is drawn from a white and Gaussian process with zero mean and constant variance. Performance evaluation is carried out via a finite-time quadratic cost that combines the second moment of the control signal, and the second moment of the difference between the initial state and the state at the final time. We show that if the time-horizon is one or two then the optimal control is a linear function of the plant’s output, while for a sufficiently large horizon a control taking on only two values will outperform the optimal affine solution. This paper complements the well-known counterexample by Hans Witsenhausen, which showed that the solution to a linear, quadratic and Gaussian optimal control paradigm might be nonlinear. Witsenhausen’s counterexample considered an optimization horizon with two time-steps (two stage control). In contrast with Witsenhausen’s work, the solution to our counterexample is linear for one and two stages but it becomes nonlinear as the number of stages is increased. The fact that our paradigm leads to nonlinear solutions, in the multi-stage case, could not be predicted from prior results. In contrast to prior work, the validity of our counterexample is based on analytical proof methods. Our proof technique rests on a simple nonlinear strategy that is useful in its own right, since it outperforms any affine solution.     

Adaptable Decentralized Service Oriented Architecture

In the Service Oriented Architecture (SOA), BPEL specified business processes are executed by non-scalable centralized orchestration engines. In order to address the scalability issue, decentralized orchestration engines are applied, which decentralize BPEL processes into static fragments at design time without considering runtime requirements. The fragments are then encapsulated into runtime components such as agents. There are a variety of attitudes towards workflow decentralization; however, only a few of them produce adaptable fragments with runtime environment. In this paper, producing runtime adaptable fragments is presented in two aspects. The first one is frequent-path adaptability that is equal to finding closely interrelated activities and encapsulating them in the same fragment to omit the communication cost of the activities. Another aspect is proportional-fragment adaptability, which is analogous to the proportionality of produced fragments with number of workflow engine machines. It extenuates the internal communication among the fragments on the same machine. An ever-changing runtime environment along with the mentioned adaptability aspects may result in producing a variety of process versions at runtime. Thus, an Adaptable and Decentralized Workflow Execution Framework (ADWEF) is introduced that proposes an abstraction of adaptable decentralization in the SOA orchestration layer. Furthermore, ADWEF architectures Type-1 and Type-2 are presented to support the execution of fragments created by two decentralization methods, which produce customized fragments known as Hierarchical Process Decentralization (HPD) and Hierarchical Intelligent Process Decentralization (HIPD). However, mapping the current system conditions to a suitable decentralization method is considered as future work. Evaluations of the ADWEF decentralization methods substantiate both adaptability aspects and demonstrate a range of improvements in response-time, throughput, and bandwidth-usage compared to previous methods.     

从青浦到嘉定 大都市无序蔓延中的先进规划

随着空前规模与速度的城市化进程,在上个十年中,上海周边的乡村地区发生了惊人的变化。在离散化的政策下,许多新城与郊区依次落成。每一个地区独特的物质条件与规章制度形成新区难以预计的多样性,同时也造成空间与功能性品质的多样化。大多数新区都依据标准步骤进行开发。一些试点新城的开发通过文本形式在西方设计师的帮助下适应中国的规范;另一些新城与街区由来自中国的新锐建筑师与规划师设计。本文主要介绍嘉定与青浦区的发展成果。     

P2P技术在网络上的应用

首先简要介绍了P2P技术的概念和特点,与传统的C/S模式进行比较,分析出P2P技术的优势,文章然后论述了P2P技术在网络上的应用及其面临的问题。     

Phosphate recovery using hybrid anion exchange: Applications to source-separated urine and combined wastewater streams

There is increasing interest in recovering phosphorus (P) from various wastewater streams for beneficial use as fertilizer and to minimize environmental impacts of excess P on receiving waters. One such example is P recovery from human urine, which has a high concentration of phosphate (200–800 mg P/L) and accounts for a small volume (∼1%) of total wastewater flow. Accordingly, the goal of this study was to evaluate the potential to recover P from source-separated and combined wastewater streams that included undiluted human urine, urine diluted with tap water, greywater, mixture of urine and greywater, anaerobic digester supernatant, and secondary wastewater effluent. A hybrid anion exchange (HAIX) resin containing hydrous ferric oxide was used to recover P because of its selectivity for phosphate and the option to precipitate P minerals in the waste regeneration solution. The P recovery potential was fresh urine > hydrolyzed urine > greywater > biological wastewater effluent > anaerobic digester supernatant. The maximum loading of P on HAIX resin was fresh urine > hydrolyzed urine > anaerobic digester supernatant ≈ greywater > biological wastewater effluent. Results indicated that the sorption capacity of HAIX resin for phosphate and the total P recovery potential were greater for source-separated urine than the combined wastewater streams of secondary wastewater effluent and anaerobic digester supernatant. Dilution of urine with tap water decreased the phosphate loading on HAIX resin. The results of this work advance the current understanding of nutrient recovery from complex wastewater streams by sorption processes.     

从分权化、市场化到全球化——改革开放以来江苏省城镇化的历程与特征

对城镇化的观察和研究需要一个多尺度的视角。基于中国当前的地域特征和制度建构,省是研究城镇化特征与机制的最佳空间单元。江苏省作为中国东部沿海发达地区的明星省份,是改革开放30年中国发展的缩影。江苏省从初级到高级的这一完整的城镇化发展过程,为观察中国城镇化的阶段、特征以及机制提供了一个非常好的案例。分权化、市场化和全球化是中国30多年来保持经济高速增长的制度基础,分权化、市场化和全球化依次主导、叠加进而复杂组合的制度演化历程,必然反映在城镇化的发展历程之中。根据三者在江苏省经济社会和城镇化发展历程中的主导作用,将改革开放30多年来江苏省的城镇化历程分为3个阶段：分权化与乡镇企业主导的城镇化（1978-1992年）,市场化与开发区建设主导的城镇化（1993-2002年）,全球化与政府主导的城镇化（2003年至今）。