Seismic hazard and risk in Shanghai and estimation of expected building damage

The People's Republic of China is in the process of rapid demographic, economic and urban change including nationwide engineering and building construction at an unprecedented scale. The mega-city of Shanghai is at the centre of China's modernisation. Rapid urbanisation and building growth have increased the exposure of people and property to natural disasters. The seismic hazard of Shanghai and its vicinity is presented from a seismogenic free-zone methodology. A PGA value of 49 cm s-2 and a maximum intensity value of VII for the Chinese Seismic Intensity Scale (a scale similar to the Modified Mercalli) for a 99% probability of non-exceedance in 50 years are determined for Shanghai city. The potential building damage for three independent districts of the city centre named Putuo, Nanjing Road and Pudong are calculated using damage vulnerability matrices. It is found that old civil houses of brick and timber are the most vulnerable buildings with potentially a mean probability value of 7.4% of this building structure type exhibiting the highest damage grade at intensity VII

Great East Japan Earthquake, JR East Mitigation Successes, and Lessons for California High-Speed Rail, MTI Report 12-37

California and Japan both experience frequent seismic activity, which is often damaging to infrastructure. Seismologists have developed systems for detecting and analyzing earthquakes in real-time. JR East has developed systems to mitigate the damage to their facilities and personnel, including an early earthquake detection system, retrofitting of existing facilities for seismic safety, development of more seismically resistant designs for new facilities, and earthquake response training and exercises for staff members. These systems demonstrated their value in the Great East Japan Earthquake of 2011 and have been further developed based on that experience. Researchers in California are developing an earthquake early warning system for the state, and the private sector has seismic sensors in place. These technologies could contribute to the safety of the California High-Speed Rail Authority’s developing system, which could emulate the best practices demonstrated in Japan in the construction of the Los Angeles-to-San Jose segment

Sähköjärjestelmän häiriöt ydinvoimalaitoksissa ja niiden simulointivaatimukset

Electrical systems perform various functions in a nuclear power plant (NPP), and they are required for the operation of many safety systems. In normal operation, all electrical systems are connected together at the high voltage level, which creates the potential for common cause failures due to faults in the plant internal or external power system. In fact, several such incidents have been reported. This thesis reviews literature related to NPP electrical system reliability and electrical disturbances. Three particularly relevant conditions (power frequency overvoltages, open phase conditions and subsynchronous oscillations) are selected for in-depth analysis. Based on the literature review and analyses, this thesis makes recommendations about simulating these conditions in COSI. COSI is a research project which aims to develop a co-simulation platform for simulating the electrical system and NPP process systems together. This thesis notes that existing electrical simulation studies have not considered process system feedback effects and other transient dynamics in much detail, and that COSI could provide insight into their effects on nuclear safety.Sähköjärjestelmät ovat tärkeitä lukuisille ydinvoimalaitoksen toiminnoille. Muun muassa monien turvallisuusjärjestelmien toiminta riippuu sähköjärjestelmistä. Normaalissa käyttötilanteessa kaikki sähköjärjestelmät kytkeytyvät yhteen suurjännitetasolla, mistä aiheutuu mahdollinen yhteisvikariski, jos laitoksen sisäisessä tai ulkoisessa sähköverkossa tapahtuu vika. Useita tämänkaltaisia tapahtumia onkin raportoitu. Tässä diplomityössä tehdään katsaus kirjallisuuteen, joka liittyy ydinvoimalaitosten sähköjärjestelmien luotettavuuteen ja sähköjärjestelmän häiriöihin. Kolme erityisen oleellista häiriötyyppiä (verkkotaajuiset ylijännitteet, vaihekatkokset ja alisynkroniset värähtelyt) valitaan lähempään tarkasteluun. Kirjallisuuskatsauksen ja tarkastelujen perusteella annetaan suosituksia näiden häiriöiden simuloimiseen COSI-projektissa. COSI on tutkimusprojekti, jossa kehitetään kosimulaatioalusta sähköjärjestelmän ja ydinvoimalaitoksen prosessijärjestelmien yhteissimulointiin. Työn mukaan aiemmissa sähköjärjestelmien simulointitutkimuksissa ei ole tarkasti selvitetty prosessijärjestelmistä aiheutuvia takaisinkytkentöjä tai muita transienttivaikutuksia. COSI voisi parantaa ymmärrystä näiden vaikutuksista ydinturvallisuuteen

Localism and energy: Negotiating approaches to embedding resilience in energy systems

Tensions are evident in energy policy objectives between centralised top-down interconnected energy systems and localised distributed approaches. Examination of these tensions indicates that a localised approach can address a systemic problem of interconnected systems; namely vulnerability. The challenge for energy policy is to realise the interrelated goals of energy security, climate and environmental targets and social and economic issues such as fuel poverty, whilst mitigating vulnerability. The effectiveness of conventional approaches is debateable. A transition to a low carbon pathway should focus on resilience, counter to vulnerability. This article draws from on-going work which evaluates the energy aspects of a Private Finance Initiative (PFI) project to refurbish and re-build a local authority’s entire stock of sheltered accommodation to high environmental standards. Initial findings suggest that whereas more conventional procurement processes tend to increase systemic vulnerability, a user focussed process driven through PFI competitive dialogue is beginning to motivate some developers to adopt innovative approaches to energy system development. Conceptually these findings strongly suggest that embedding ‘Open Source’ principles in energy system development acts to work against systemic vulnerabilities by embedding resilience

Vibration analysis of reconditioned high-speed electric motors

This paper discusses the issue of assessing the condition of three-phase induction motors (which are used as power units for tools on manufacturing lines in the furniture industry) following major repairs. These high-speed motors differ from standard motors in higher frequency power input, more durable bearings and reinforced structure of the terminal part of the rotor shaft. The rotational speed of the rotor is 10,000-18,000 rpm. Such high values of rotational speed trigger a situation in which exceeding the allowable limit of residual unbalance for the rotor unit damages the motor. The damage might necessitate a comprehensive repair. Such cases are frequent. The conducted studies resulted in designing a vibration analysis for assessing the condition of reconditioned high-speed motors (a method for controlling the quality of repairs). Both high- and low-frequency analyses with a signal selection module and the basic general measurements were applied. The analysis provides the possibility of verifying the efficacy of reconditioning in relation to the mechanical validity of the repaired motors

Improved transient earth fault clearing on solid and resistance earthed MV netwworks

Includes bibliographical references.The aim of this thesis is to endeavour to develop, through a literature study, a method or methods whereby transient earth faults on neutral earthed MV networks may be cleared without customer supply interruptions, without compromising public safety and without compromising network integrity. In order to propose such a method, or methods, it is important to understand the various earthing practices employed in MV networks in terms of network behaviour under earth fault conditions, as this may influence network component insulation rating requirements, as well as the way in which such a system may function

ELECTRICAL OVERCURRENT PROTECTION GRADING IN V4D

Selective Coordination contributes to the localization of an overcurrent condition to restrict outages to the circuit or equipment affected, accomplished by the choice of overcurrent protective devices and their ratings and settings. Selective Coordination is critical for the reliability of electrical distribution system and must be analyzed and test regularly. A properly engineered and installed system will allow only the nearest upstream overcurrent protective device to open for both overload and all types of short-circuits, leaving the remainder of the systems undisturbed and preserving continuity of service. The aim of this study is to perform a Coordination and Overload study for the electrical installation in Village-4D T1, in order to know the root causes of the continuous tripping of its main Circuit Breaker which results in frequent power outage in the area. The revision of past researches was the first step taken toward understanding the concept involving protections; followed by a series of site inspections which helped gather the relevant data needed for the study such as the types of protective devices and their arrangement as well as the ratings. The methodology required a sensitivity analysis of the CBs in the area of study and Overload study in which fault levels were simulated using Simulink/MATLAB. The preliminary results of the study based on CBs level of sensitivity showed that V4D protective devices level of sensitivity is medium, therefore less prone to nuisance tripping outside the nominal tripping current. Thus sensitivity is not the factor causing the breaker to trip. However the results from the overload study show that the increasing number of overheating appliances used by students causes the circuit to overload, thus tripping the main breaker

Study of a unified hardware and software fault-tolerant architecture

A unified architectural concept, called the Fault Tolerant Processor Attached Processor (FTP-AP), that can tolerate hardware as well as software faults is proposed for applications requiring ultrareliable computation capability. An emulation of the FTP-AP architecture, consisting of a breadboard Motorola 68010-based quadruply redundant Fault Tolerant Processor, four VAX 750s as attached processors, and four versions of a transport aircraft yaw damper control law, is used as a testbed in the AIRLAB to examine a number of critical issues. Solutions of several basic problems associated with N-Version software are proposed and implemented on the testbed. This includes a confidence voter to resolve coincident errors in N-Version software. A reliability model of N-Version software that is based upon the recent understanding of software failure mechanisms is also developed. The basic FTP-AP architectural concept appears suitable for hosting N-Version application software while at the same time tolerating hardware failures. Architectural enhancements for greater efficiency, software reliability modeling, and N-Version issues that merit further research are identified