HAZOP-proof ammonia plant: A new way of defining a safe and reliable design

This new technique, which meets interacting design criteria of a 1,800-MTPD ammonia project, offers special safety features and withstands a detailed HAZOP study.     

The role of mobile network operators in next-generation public safety services

Field of researchThis research is in the field of public safety communications in mobile broadband 4G/5G networks. The focus is on mobile network operators and their business opportunities in the public safety market.PurposeThe purpose of this research is to provide a review of ongoing public safety mobile broadband projects in which mobile operators play a key role. In addition, a business model analysis is presented to determine the role of mobile operators in these projects. A comparison of the two key business models is also included to reveal their general characteristics.Methods and dataThe research used a qualitative method, an inductive case study. This method was used to draw general conclusions from a small number of case studies based on ongoing public safety mobile broadband projects. The Casadesus-Masanell and Ricart framework and the business model canvas were used to analyse and compare the two key business models discussed. Data were collected from a variety of sources, including company reports, press releases, international events and conferences, and selected interviews with managers in charge.FindingsThe results show that mobile operators have new business opportunities in the public safety market. Their existing mobile networks can be used for public safety services with certain enhancements. Within existing projects, mobile operators have different business models. The two analysed models were found to require different resources and offer different business opportunities for mobile operators. Procurement authorities responsible for selecting business models are encouraged to pay attention to the choice of model based on, for example, strategic objectives.ValueVery little research has been done on the business opportunities of mobile operators in the public safety market. In this area, this study lays the groundwork for new research. Procurement authorities can use the results when deciding on the business model. Mobile operators can benefit from these results by better understanding their own roles in public safety projects and when assessing the business opportunities of a particular project.     

Competition in UK mobile communications

Since mobile communications began in the United Kingdom in 1985, with the licensing of two cellular networks, the number of subscribers has grown to eight million. Much of this growth has occurred in the past five years, which have also seen the emergence of new competition in the form of two PCN operators. The aim of this paper is to trace the development of competition between network operators over the period from 1985. We first present technological and regulatory considerations that are used as a background to understand relevant features related to the structure of the industry and to the growth of subscribers. The central part of the paper reviews the four operators’ strategies, which are interpreted with the help of insights from economic theory.     

An efficient hybrid genetic algorithm for the multi-product multi-period inventory routing problem

The inventory routing problem (IRP) addressed in this study is a many-to-one distribution network consisting of an assembly plant and many distinct suppliers where each supplies a distinct product. We consider a finite horizon, multi-periods, multi-suppliers and multi-products where a fleet of capacitated homogeneous vehicles, housed at a depot, transport products from the suppliers to meet the demand specified by the assembly plant in each period. The demand for each product is deterministic and time varying. A mathematical formulation of the problem is given and CPLEX 9.1 is run for a finite amount of time to obtain lower and upper bounds. A hybrid genetic algorithm, which is based on the allocation first route second strategy and which considers both the inventory and the transportation costs, is proposed. In addition to a new set of crossover and mutation operators, we also introduce two new chromosome representations. Several medium and small sized problems are also constructed and added to the existing data sets to show the effectiveness of the proposed approach.     

Effective competition and ineffective mobile industry regulation in South Africa

The most striking feature of South Africa’s mobile market is the skewed allocation of spectrum and a seemingly endless sequence of failed attempts to hold an auction for it. A shortage of spectrum (or the inefficient assignment of it) is blamed, among other things, for South Africa’s relatively slow LTE 4G speeds. Through historical accident, the country has two mobile data networks in addition to the four licensed mobile operators. The response of operators has been to innovate using roaming and network sharing agreements; as we explore in this paper, these have become the de facto spectrum allocation process.This paper looks at how the de facto industry structure has been moulded by spectrum holdings and sharing arrangements and asks how spectrum management could be improved. We observe that, although the number of mobile operators has effectively been reduced to 3 (a number which would raise concern in some circles), there exist a variety of arrangements between those three and other spectrum and network operators. The smallest of the current three mobile operators is still not able to offer a nationwide mobile service without a roaming agreement but, at the same time, the two larger operators depend critically on spectrum and roaming agreements themselves, mainly with the two physical data network operators that function as wholesale providers.The Independent Communications Authority of South Africa (ICASA) was established as a consequence of a new constitution that was adopted in 1996 and it helped to create new institutional arrangements for the burgeoning mobile industry. The authority has nevertheless continued to be hampered, as we shall demonstrate, by political imperatives. This has been pointed out by other authors over the past twenty years and we add to this body of evidence by considering the spectrum auction planned (again) for 2021.The “2021” auction is in fact an iteration of the auction originally announced in May 2010 and then abandoned (Song, 2011). The same thing happened again in 2016 (Paelo & Robb, 2020). Late in 2020, the regulator again announced an auction, due to take place during 2021 but by the second quarter of the year, two of the four national operators had already obtained a court injunction to stop it. The process is intertwined with a political imperative to establish a public wireless open-access network, which we discuss in detail.We describe how the industry has navigated around policy and regulatory dysfunction and how competitive interaction among the South African operators has managed to prevail. Following Hausman & Taylor’s (2013) lead in their work on the United States, in this paper we provide a commentary on apparently perverse outcomes from significant regulatory, judicial and legislative actions (or, perhaps more accurately, inactions) governing the South African mobile telecommunications industry from the commencement of the current constitutional arrangements in 1996 to the present.     

Adaptive genetic algorithm for lot-sizing problem with self-adjustment operation rate

This paper presents a new adaptive genetic algorithm (GA) to escape local optimum solutions of the traditional lot-sizing rules. In this GA, the timing of replenishment is encoded as a string of binary digits (a chromosome). Each gene in that chromosome stands for a period. Standard GA operators are used to generate new populations. These populations are evaluated by a fitness function using the replenishment scheme of solution based on the total cost. Through this evaluation, the rates of GA operators for the next generation are automatically adjusted based on the rate of survivor offsprings, which are generated by corresponding operators. The oriented search procedure using these self-adjustment rates of operator schemes can give faster and better solutions. Some experimental results confirm the theoretical judgment.     

Environmental implications of market structure: Shale gas and electricity markets

We examine the environmental implications of market structure using the exogenous variation in the price of natural gas paid by U.S. electric power producers in the aftermath of the Shale Boom. We find that electric power producers were more responsive to fuel prices in vertically integrated markets than in restructured markets, and we explore the underlying factors driving this heterogeneity in responses. Although differences in the capacity of the most efficient gas power plants between the two market structures are the most important factor, we consider others. The heterogeneity in the response of power plant operators to fuel prices has material implications for carbon dioxide emissions.     

Mobile money,family assistance and welfare in Cameroon

This paper aims to investigate the effect of mobile money services on the welfare in Cameroon. It specifically verifies whether the welfare of people benefiting from family assistance is improved via the mobile money services offered by the two main operators in the country, namely: Orange and Mtn. The data used come from the « FinScope Consommateur Cameroun » Survey carried out in 2017 by the National Institute of Statistics (INS). Based on the propensity scores estimations, this study shows a positive and significant effect of mobile money on welfare. However, among the operators, Orange has a better impact compared to Mtn which does not present a significant effect. These results call on the authorities in charge of the development and implementation of financial inclusion policies to recognize the interest of digital financial services at the heart of financial inclusion strategies for the welfare of the poor.     

Gleichzeitigkeit als Leistungsgröße: Inter- und Intra-Klassen-Leistung volatiler EE-Einspeiser

The energy transition focuses on the expansion and enhancement of distribution grids and the integration of decentralized renewable generation plants. The integration of decentralized plants presents a major challenge for distribution system operators in particular. The planning and dimensioning of energy grids requires knowledge of all integrated generating units and power consumers, as well as their power ratings. Furthermore, knowledge about the diversity of renewable power plant types enables distribution system operators and scientists to selectively or cumulatively assess the maximum feed-in capacity. This is particularly important for the assessment of case studies or border scenarios. The purpose of this article is the evaluation of the maximum simultaneous feed-in power of PV and wind power plants. Furthermore, the ratio of the installed power to the maximum power generated by renewable power plants is also investigated. The diversity factor describes the ratio of the sum of all individual load’s maximum powers to the number of loads. This simultaneity can also be adapted to renewable power plants. However, it is differentiated here between simultaneous power within one renewable power plant type (intra-class performance) and simultaneous power of different renewable power plant types (inter-class performance). In cooperation with one of the largest national distribution network operator, regression lines are approximated by statistical analyzes, in order to determinate the diversity of the Central German area.     

Neue Anforderungen an optimierende Energiesystemmodelle für die Kraftwerkseinsatz- und Zubauplanung bei begrenzten Netzkapazitäten

Recent changes in energy economic frameworks conditions lead to new requirements for energy systems models. Particularly in Germany, structural and locational changes in the power plant sector can be observed. Above all, this is due to the liberalisation process entailing the legal unbundling of system operators and generation companies as well as to the ambitious aims for the extension of wind energy. Consequently, modelling energy systems as single node systems, in which network constraints are neglected, can lead to suboptimal results. Most energy systems models offer the possibility to limit interregional energy exchange capacities. However, these so-called transhipment models normally neglect the actual load flows. Yet, there are several possibilities to adequately consider the characteristics of power transmission. In this paper, the most popular approaches, which are used in particular technical applications, such as the AC- (Alternating Current), the DC- (Direct Current) and the PTDF- (Power Transfer Distribution Factors) approach are introduced and discussed with respect to their application in energy systems models. In addition, first experiences with their implementations are presented.     

TP case study: fixed–mobile interconnection in India

The Telecommunications Regulatory Authority of India (TRAI) attempted, in late 1999, to introduce the calling party pays (CPP) regime for mobile cellular services, with a corresponding revenue-sharing arrangement between fixed and mobile operators. According to the revenue-sharing proposal, mobile operators in India were to be compensated for carrying traffic to and from the fixed networks. Under their original license conditions, fixed operators (usually one of the two state-owned incumbents) were not paying mobile operators for terminating calls on their networks. However, mobile operators had to compensate the state-owned incumbent for terminating traffic. This unfavourable environment for mobile operators has meant that mobile services have not been able to reach their full potential in India. There was great disappointment within the mobile industry when the TRAI's CPP order was overturned by the Supreme Court of India in early 2000, due to lack of jurisdiction. Since then, the enabling legislation has been amended. It is hoped that the new provisions of the TRAI Act will empower the regulator to establish a level playing field for mobile network operators. It is only through the creation of a suitable framework for interconnection that the TRAI will be able to ensure the success of telecommunications reform in India.     

Machine repairing models for production systems

In this paper we consider manufacturing systems of m identical unreliable machines producing one type of product. The operating time of each machine is exponentially distributed. The repairing process of a machine requires more than one phase. In each phase, the repair time is exponentially distributed and more than one operator may be required for fixing a broken machine. Here we consider two models of manufacturing systems. In the first model, there are r operators assigned in one server to repair a broken machine. The repairing rate in each phase depends on the number of operators there. This is a generalized model discussed in Buzacott and Shanthikumar [11]. We then consider a two-phase repairing model. Two groups of operators are assigned in the two phases. Each operator can handle one broken machine in each phase individually. This model is a generalization of Eben–Chaime's model [8]. Average profits are derived for both models and can be optimized by suitable allocation of the number of machines and operators in the systems.     

Customer retention,loyalty, and satisfaction in the German mobile cellular telecommunications market

Customer retention (CR), loyalty (CL), and satisfaction (CS) are important (intermediate) goals for telecommunication network operators on their way to superior economic success in the liberalised German market. Therefore, drawing on a sample of 684 residential customers of digital cellular network operators in Germany this study tests hypotheses suggesting that CR, CL, and CS should be treated as differential constructs which are causally inter-linked. LISREL analyses support a two-staged model in which overall CS has a significant impact on CL which in turn influences a customer's intention to terminate/extend the contractual relationship with his mobile cellular network operator (=CR). Mobile service price and personal service benefit perceptions as well as (lack of) number portability between various cellular operators were identified as supply-related variables with the strongest effects on CR. Mobile network operators’ perceived customer care performance had no significant impact on CR. The findings suggest that an important lever for regulators to promote competition in cellular markets is the enforcement of efficient number portability procedures between mobile network operators.     

Die Berücksichtigung von Spitzenkappung in der Anreizregulierung

The model of temporary disconnection of renewable energy in case of high energy injection and low demand is thought to be an effective method for reducing investments in electricity networks. However, plant owners need to be reimbursed for foregone sales. According to the currently discussed draft of the Amendment of the German Incentive Regulation Ordinance, these costs can be rolled over to the consumer on a yearly basis, but are part of the cost benchmark with their base year values. This paper shows that this model sets incentives for optimal investments in electricity networks, but violates the participation constraint: Net operators will be exposed to a severe risk of worsening their position in the cost benchmark. In expectation, they will generate losses and investors have no incentive to invest in electricity networks. This problem can be solved by allowing net operators to roll over costs to customers, while considering average reimbursement fees in the cost benchmark.     

电信重组引发五大悬念

重组的具体过程依然会显得漫长而艰辛,并充满各种不确定性和悬念。在经过了几年的猜谜游戏之后,中国电信行业第三次重组方案终于尘埃落定。5月24日14:00,工业和信息化部、国家发改委以及财政部联合发布中国电信业重组公告:基于电信行业现状,为实现改革目标,鼓励中国电信收购中国联通CDMA网(包括资产和用户),中国联通与中     

Strategic choice and broadband divergence in the transition to next generation networks: Evidence from Canada and the U.S.

This article investigates how infrastructure competition among broadband network infrastructure operators in Canada and the U.S. has influenced their incentives to increase fixed broadband connection speeds and invest in next generation fiber-to-the-premises (FTTP) technologies. The evolution of measured broadband speeds since the late 2000s documents growing differences in the incentives of dominant broadband operators to respond to demand for higher speed connectivity by increasing connectivity speeds they deliver to their customers. Dominant network operators in Canada have shown relatively stronger incentives than their counterparts in the U.S. to invest in and increase the capacity of legacy platforms. In the U.S. FTTP deployment incentives have been somewhat stronger, but network operators have been more reluctant to upgrade legacy technologies to deliver higher speeds. Diversity of strategic choices by large operators helps explain increasing regional and local broadband infrastructure gaps within the two countries. A high dividend payout financial strategy and increasing vertical integration appear to enhance the potential for overinvestment and inefficient duplication in legacy platforms by competing infrastructure providers.     

企业效绩评价与经营者年薪挂钩研究

经营者年薪一般包括基本年薪和效益年薪两个部分。尽管全国各地普遍开展了经营者年薪制试点，但对年薪的确定很不规范，特别是对经营者经营业绩的评价缺乏科学手段。本文在运用企业效绩评价体系对经营者业绩进行科学评价的基础上，对如何确定经营者基本年薪和效益年薪，建立了一个基本模型，并选择了150户大型企业进行了模拟测算，使年薪制的实施具备了比较科学的技术基础。     

Die Marktprämie im EEG 2012: Ein sinnvoller Beitrag zur Markt- und Systemintegration erneuerbarer Energien?

With the share of renewable energies within the electricty sector rising, improving their market integration (i.e. inclusion in the steering and remuneration processes of the electricity market) and system integration (i.e. enhanced responsibility for grid stability) is of increasing importance. To transform the energy system efficiently while ensuring security of supply, it is necessary to increase the alignment of renewable electricity production with short- and long-term market signals. The German Renewable Energy Sources Act 2012 introduced the market premium to provide market experience to renewable plant operators and incentives for demand-oriented electricity production. Shortly after its introduction, the instrument is already being criticised as ineffective and expensive. Building on early experiences, this article examines whether the market premium in its current design improves market and/or system integration, and if it seems suitable in principle to contribute to these aims (effectiveness). Also, potential efficiency gains and additional costs of “administering integration” are discussed (efficiency). While market integration in a strict sense (i.e. exposing renewables to price risks) is not the purpose of the market premium, it has successfully increased participation in direct marketing. However, windfall profits are high, and the benefits of gradually leading plant operators towards the market are questionable. Incentives for demand-oriented electricity production are established, but they prove insufficient particularly in the case of intermittent renewable energy sources. A continuation of the instrument in its current form therefore does not seem recommendable. To conclude, potential alternative solutions are presented.     

基于STM32的太阳模拟器控制系统设计

聚焦型太阳模拟器应用于光热发电相关试验,主要由风冷系统、光学系统、机械系统、控制系统组成。为了消除系统的人工安装误差、减小光斑调整误差,设计了基于STM32处理单元,结合PID算法,采用RS485通信标准,以液晶触摸屏为输入输出单元的太阳模拟器控制系统。该系统主要包括氙灯光强度控制、氙灯阴极温度控制、氙灯单元俯仰、平移控制等模块。通过对控制系统的搭建,实现了光斑面积与焦平面的位置调整,以及氙灯阴极温度的检测与控制,有效解决了多光源系统焦点光斑汇聚重合的问题。