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Scholarly Pursuits: A Victorian San Francisco M...
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“Something is rotten in the state of Berkeley.” (1881 Blue and Gold Yearbook, University of California, Berkeley)In Scholarly Pursuits, the sixth full-length book in the USA Today best-selling Victorian San Francisco mystery series, Locke explores life in University of California, Berkeley campus, in 1881. Laura and her friends face the remarkably modern problems of fraternity hazings, fraught romantic relationships, and fractious faculty politics.  While Annie and Nate Dawson and friends and family in the O’Farrell Street boardinghouse await a blessed event, Laura Dawson finds herself investigating why a young Berkeley student dropped out of school in the fall of 1880. No one, including her friend Seth Timmons, thinks this is a good idea, since she is juggling a full course load with a part-time job, but she can’t let the question of what happened to her friend go unanswered. Not when it means that other young women might be in danger. This cozy historical mystery of romantic suspense is set in the period immediately after the fifth book in the series, Pilfered Promises, and two novellas, Kathleen Catches a Killer and Dandy Delivers. However, it can be listened to as a stand-alone. 1. Language: English. Narrator: Alexandra Haag. Audio sample: http://samples.audible.de/bk/acx0/169686/bk_acx0_169686_sample.mp3. Digital audiobook in aax.

Anbieter: Audible
Stand: 23.02.2020
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Motor City Burning , Hörbuch, Digital, 1, 575min
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From the critically acclaimed author of Motor City, Detroit comes alive in a powerful and thrilling novel set amid the chaos of the 1960s race riots and the serenity of baseball's opening day. Willie Bledsoe, once an idealistic young black activist, is now a burnt-out case. After leaving a snug berth at Tuskegee Institute to join the Student Nonviolent Coordinating Committee, he has become bitterly disillusioned with the civil rights movement and its leaders. He returns home to Alabama to try to write a memoir about his time in the cultural whirlwind, but the words fail to come. The surprise return of his Vietnam veteran brother in the spring of 1967 gives Willie a chance to drive a load of smuggled guns to the Motor City - and make enough money to jump-start his stalled dream of writing his memoir. There, at Tiger Stadium on Opening Day of the 1968 baseball season - postponed two days in deference to the funeral of Martin Luther King, Jr. - Willie learns some terrifying news: the Detroit police are still investigating the last unsolved murder from the bloody, apocalyptic riot of the previous summer, and a white cop named Frank Doyle will not rest until the case is solved. And Willie is his prime suspect. Bill Morris' rich and thrilling novel sets Doyle's hunt amid the history of one of America's most tortured and fascinating cities, as Doyle and Willie struggle with Detroit's deep racial divide, with revenge and forgiveness, and with the realization that justice is rarely attainable - and rarely just. 1. Language: English. Narrator: Richard Small. Audio sample: http://samples.audible.de/bk/blak/006757/bk_blak_006757_sample.mp3. Digital audiobook in aax.

Anbieter: Audible
Stand: 23.02.2020
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Deadhouse: Life in a Coroner's Office , Hörbuch...
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Deadhouse: Life in a Coroner's Office chronicles the exploits of a diverse team of investigators at a coroner's office in Pittsburgh. Ed Strimlan is a doctor who never got to practice medicine. Instead he discovers how people died. Mike Chichwak is a stolid ex-paramedic, respected around the office for his compassion and doggedness. Tiffani Hunt is 21, a single mother who questions whether she wants to spend her nights around dead bodies. All three deputy coroners share one trait: a compulsive curiosity. A good thing too, because any observation at a death scene can prove meaningful. A bag of groceries standing on a kitchen counter, the milk turning sour. A broken lamp lying on the carpet of an otherwise tidy living room. When they approach a corpse, the investigators consider everything. Is the victim face-up or down? How stiff are the limbs? Are the hands dirty or clean? By the time they bag the body and load it into the coroner's wagon, Tiffani, Ed, and Mike have often unearthed intimate details that are unknown even to the victim's family and friends. The intrigues of investigating death help make up for the bad parts of the job. There are plenty of burdens - grief-stricken families, decomposed bodies, tangled local politics, and gore. And maybe worst of all is the ever-present reminder of mortality and human frailness. Deadhouse also chronicles the evolution of forensic medicine, from early rituals performed over corpses found dead to the controversial advent of modern forensic pathology. It explains how pathologists "read" bullet wounds and lacerations, how someone dies from a drug overdose or a motorcycle crash or a drowning, and how investigators uncover the clues that lead to the truth. The book is published by University Press of Mississippi. The audiobook is published by University Press Audiobooks. 1. Language: English. Narrator: Tim Lundeen. Audio sample: http://samples.audible.de/bk/acx0/123321/bk_acx0_123321_sample.mp3. Digital audiobook in aax.

Anbieter: Audible
Stand: 23.02.2020
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A Medium-Voltage Multi-Level DC/DC Converter wi...
49,80 € *
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Renewable energy sources are becoming increasingly important these days. The nuclear power phase-out in Germany and the limited amount of fossil energy resources will lead to further expansion of renewables. This might be directly linked with a change in the distribution and transportation grid. As early as in the 1990's ABB introduced a DC grid vision in a Europe 20xx scenario [1]. DC transmission systems are already used in large offshore wind-park installations and offer beside technical advantages (increased efficiency, smaller transformers) also economic benefits [2]. From industry perspective, ABB recently introduced an onboard DC-grid for marine power and propulsion systems with a grid voltage of 1000 V and up to 20 MW of power [3]. But also DC distribution grids in the mediumvoltage level range have come into the focus of research in the last years [4]. According to [1], DC offers significant loss reduction, less visual impact, lower electromagnetic fields. Furthermore it is the only solution for sub-sea connections longer than 60 km. One key component for the required technology is the DC/DC converter, which is also used in solid state transformers [5]. DC/DC converters for small power and low-voltage levels are well known today. The dual-active bridge converter, consisting of two H-bridge or halfbridge converters, offers bidirectional power flow, galvanic isolation and is a well-established topology [6], [7]. The voltage drop over the effective stray inductance of the transformer, which corresponds to the transferred power, is controlled by the phase-shift between both transformer voltages. An overview of the different galvanically isolated DC/DC converters is given in [8] and [9]. Recent research is investigating the potential to optimize the dual-active H-bridge converter using a transformer zero-voltage level [10]. The zero-voltage level is obtained by switching-on either both upper or both lower switches of the H-bridge simultaneously. The principle of realizing a zero-voltage level by phase-shifting both halfbridges of the H-bridge was already introduced with the single-active bridge, also known as the phase-shifted bridge [11]. Medium-voltage high-power realisations are very rare. According to Table 2.2 in [12], there is no demonstrator of a galvanically isolated bidirectional DC/DC converter with a voltage rating of at least 6 kV and a minimum power rating of 100 kW known to the author. Few converter concepts exist with similar or higher ratings, but these are bound to research environments and are still under development. In case the classical H-bridge or half-bridge configuration is used, the maximum DC-link voltage is limited by the blocking voltage of the power electronic switches. To overcome this limitation a series connection of dual-active bridges can be used. Alternatively, a direct series connection of switches is conceivable and requires measures to limit statically and dynamically the maximum voltage across each single switch [4]. For example, balancing resistors and RC-snubbers or intelligent gate driver units are used. But altogether losses are produced continuously. The maximum voltage across the switches can be limited by e.g. clamping diodes or active switches leading to multi-level converter topologies for the dualactive bridge. Due to the current flow through the clamping diodes several sub-operations modes can be distinguished. Even with a single three-level NPC (neutral point clamped converter [13]) or ANPC (active neutral point clamped [14]) half-bridge configuration, natural voltage doubling in one-phase configurations is possible. With every additional voltage-level, the degree of freedom for the operation of the converter can be increased. In literature there are only a few publications with an three-level NPC DC/DC converter, but either with an unidirectional power flow or not using the additional degree of freedom [15]. Higher voltagelevel topologies used in a galvanically isolated dual-active bridge configuration could not be found [16]. They are named multi-level DC/DC converters. A structured analysis of the entire load and operation range of the three-level NPC / two-level one-phase dual-active bridge or of a multi-level DC/DC converter, including all analytical formulae to design and optimize the converter is not known to the author. Multilevel DC/DC converters are investigated in this thesis exemplarily for the three-level NPC / two-level one-phase dual-active bridge DC/DC converter. The derived analytical approach can be applied analogously to more-level DC/DC converter topologies. In this thesis only topologies with clamping diodes are considered. Other multi-level topologies like flying capacitor converters can be used likewise, but they are not considered in this dissertation. Chapter 2 includes definitions for the comparison of different topologies and formulae for the optimization of the converters. This includes power definitions as well as the derivation of formulae adapted to multi-level DC/DC converters to compare the core losses or transformer utilization of different topologies. Design aspects of the transformer are covered as far as they concern multi-level DC/DC converters. The design of the transformer in general is not part of this chapter due to sufficiently published literature on this topic. In Chapter 3 the three-level NPC / two-level one-phase dual-active bridge DC/DC converter as an example of a multi-level DC/DC converter is introduced. In contrast to the well-known dual-active bridge with H-bridge or half-bridge converters, a three-level neutral point clamped converter on the high-voltage side replaces the H-bridge. A structured analysis of all main operation modes with an exhaustive analytical description with all it's formulae is presented. Two operation modes are identified to operate this topology over the full load range. These two main operation modes are divided into sub-operation modes in Chapter 4. Each sub-operation mode is distinguished by the transformer current at the switching instants. Furthermore, each sub-operation mode is characterized by the power electronic switching behaviour: hard-switched, zero-voltage turn-on switched or near zero-current switched. Formulae to operate the converter in a selected sub-operation mode are given. From these equations the dependence and limitations on the transferred power and voltage transformation ratio can be extracted. This chapter provides the mathematical basis to use the whole optimization potential of the converter. In Chapter 5 a control structure for multi-level DC/DC converters is proposed. It consists of a feed-forward and closed-loop control. The feed-forward linearises the converter's behaviour for the control and allows a fast reaction to new reference values. The PI closed-loop controller levels out losses and other errors not covered by the analytical equations. Further topics are the gate signal generation and the steady-state start of the converter to avoid a possible saturation of the transformer core at the PWM start. At the end of this chapter, necessary information will be presented to design and realize a multi-level DC/DC converter in hardware. Chapter 6 describes a hardware realization of a 3.3 kV. 6 kV, 100 kW galvanically isolated three-level NPC / two-level one-phase dual-active bridge DC/DC converter, which seems to be unique, at least in the university environment [12]. This DC/DC converter is part of a built battery energy storage system and test facility for the characterization of batteries in the kV range. Besides practical design aspects as, for example, the construction of a low-inductance two-layer busbar for the three-level NPC converter, a comparison of measurement and simulation results is given, showing good concordance of the simulation and the analytical description with the real system. The chapter closes with measurement results inside the battery energy storage system, depicting the excellent controllability and sensor resolution of the converter. Chapter 7 shows the application of the derived analytical approach to a five-level NPC / two-level one-phase dual-active bridge for the first operation mode. An extension to threephases of the three-level NPC / two-level one-phase dual-active bridge is presented, before the N-level NPC / N-level NPC multi-phase dual-active bridge converter is introduced. The thesis closes with a summary in Chapter 8. This chapter discusses possible future work, for example the influence of the transformer configuration in multi-phase topologies or the comparison between multi-level DC/DC converters and the series-connection of dualactive bridges with H-bridge converters.

Anbieter: buecher
Stand: 23.02.2020
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A Medium-Voltage Multi-Level DC/DC Converter wi...
49,80 € *
ggf. zzgl. Versand

Renewable energy sources are becoming increasingly important these days. The nuclear power phase-out in Germany and the limited amount of fossil energy resources will lead to further expansion of renewables. This might be directly linked with a change in the distribution and transportation grid. As early as in the 1990's ABB introduced a DC grid vision in a Europe 20xx scenario [1]. DC transmission systems are already used in large offshore wind-park installations and offer beside technical advantages (increased efficiency, smaller transformers) also economic benefits [2]. From industry perspective, ABB recently introduced an onboard DC-grid for marine power and propulsion systems with a grid voltage of 1000 V and up to 20 MW of power [3]. But also DC distribution grids in the mediumvoltage level range have come into the focus of research in the last years [4]. According to [1], DC offers significant loss reduction, less visual impact, lower electromagnetic fields. Furthermore it is the only solution for sub-sea connections longer than 60 km. One key component for the required technology is the DC/DC converter, which is also used in solid state transformers [5]. DC/DC converters for small power and low-voltage levels are well known today. The dual-active bridge converter, consisting of two H-bridge or halfbridge converters, offers bidirectional power flow, galvanic isolation and is a well-established topology [6], [7]. The voltage drop over the effective stray inductance of the transformer, which corresponds to the transferred power, is controlled by the phase-shift between both transformer voltages. An overview of the different galvanically isolated DC/DC converters is given in [8] and [9]. Recent research is investigating the potential to optimize the dual-active H-bridge converter using a transformer zero-voltage level [10]. The zero-voltage level is obtained by switching-on either both upper or both lower switches of the H-bridge simultaneously. The principle of realizing a zero-voltage level by phase-shifting both halfbridges of the H-bridge was already introduced with the single-active bridge, also known as the phase-shifted bridge [11]. Medium-voltage high-power realisations are very rare. According to Table 2.2 in [12], there is no demonstrator of a galvanically isolated bidirectional DC/DC converter with a voltage rating of at least 6 kV and a minimum power rating of 100 kW known to the author. Few converter concepts exist with similar or higher ratings, but these are bound to research environments and are still under development. In case the classical H-bridge or half-bridge configuration is used, the maximum DC-link voltage is limited by the blocking voltage of the power electronic switches. To overcome this limitation a series connection of dual-active bridges can be used. Alternatively, a direct series connection of switches is conceivable and requires measures to limit statically and dynamically the maximum voltage across each single switch [4]. For example, balancing resistors and RC-snubbers or intelligent gate driver units are used. But altogether losses are produced continuously. The maximum voltage across the switches can be limited by e.g. clamping diodes or active switches leading to multi-level converter topologies for the dualactive bridge. Due to the current flow through the clamping diodes several sub-operations modes can be distinguished. Even with a single three-level NPC (neutral point clamped converter [13]) or ANPC (active neutral point clamped [14]) half-bridge configuration, natural voltage doubling in one-phase configurations is possible. With every additional voltage-level, the degree of freedom for the operation of the converter can be increased. In literature there are only a few publications with an three-level NPC DC/DC converter, but either with an unidirectional power flow or not using the additional degree of freedom [15]. Higher voltagelevel topologies used in a galvanically isolated dual-active bridge configuration could not be found [16]. They are named multi-level DC/DC converters. A structured analysis of the entire load and operation range of the three-level NPC / two-level one-phase dual-active bridge or of a multi-level DC/DC converter, including all analytical formulae to design and optimize the converter is not known to the author. Multilevel DC/DC converters are investigated in this thesis exemplarily for the three-level NPC / two-level one-phase dual-active bridge DC/DC converter. The derived analytical approach can be applied analogously to more-level DC/DC converter topologies. In this thesis only topologies with clamping diodes are considered. Other multi-level topologies like flying capacitor converters can be used likewise, but they are not considered in this dissertation. Chapter 2 includes definitions for the comparison of different topologies and formulae for the optimization of the converters. This includes power definitions as well as the derivation of formulae adapted to multi-level DC/DC converters to compare the core losses or transformer utilization of different topologies. Design aspects of the transformer are covered as far as they concern multi-level DC/DC converters. The design of the transformer in general is not part of this chapter due to sufficiently published literature on this topic. In Chapter 3 the three-level NPC / two-level one-phase dual-active bridge DC/DC converter as an example of a multi-level DC/DC converter is introduced. In contrast to the well-known dual-active bridge with H-bridge or half-bridge converters, a three-level neutral point clamped converter on the high-voltage side replaces the H-bridge. A structured analysis of all main operation modes with an exhaustive analytical description with all it's formulae is presented. Two operation modes are identified to operate this topology over the full load range. These two main operation modes are divided into sub-operation modes in Chapter 4. Each sub-operation mode is distinguished by the transformer current at the switching instants. Furthermore, each sub-operation mode is characterized by the power electronic switching behaviour: hard-switched, zero-voltage turn-on switched or near zero-current switched. Formulae to operate the converter in a selected sub-operation mode are given. From these equations the dependence and limitations on the transferred power and voltage transformation ratio can be extracted. This chapter provides the mathematical basis to use the whole optimization potential of the converter. In Chapter 5 a control structure for multi-level DC/DC converters is proposed. It consists of a feed-forward and closed-loop control. The feed-forward linearises the converter's behaviour for the control and allows a fast reaction to new reference values. The PI closed-loop controller levels out losses and other errors not covered by the analytical equations. Further topics are the gate signal generation and the steady-state start of the converter to avoid a possible saturation of the transformer core at the PWM start. At the end of this chapter, necessary information will be presented to design and realize a multi-level DC/DC converter in hardware. Chapter 6 describes a hardware realization of a 3.3 kV. 6 kV, 100 kW galvanically isolated three-level NPC / two-level one-phase dual-active bridge DC/DC converter, which seems to be unique, at least in the university environment [12]. This DC/DC converter is part of a built battery energy storage system and test facility for the characterization of batteries in the kV range. Besides practical design aspects as, for example, the construction of a low-inductance two-layer busbar for the three-level NPC converter, a comparison of measurement and simulation results is given, showing good concordance of the simulation and the analytical description with the real system. The chapter closes with measurement results inside the battery energy storage system, depicting the excellent controllability and sensor resolution of the converter. Chapter 7 shows the application of the derived analytical approach to a five-level NPC / two-level one-phase dual-active bridge for the first operation mode. An extension to threephases of the three-level NPC / two-level one-phase dual-active bridge is presented, before the N-level NPC / N-level NPC multi-phase dual-active bridge converter is introduced. The thesis closes with a summary in Chapter 8. This chapter discusses possible future work, for example the influence of the transformer configuration in multi-phase topologies or the comparison between multi-level DC/DC converters and the series-connection of dualactive bridges with H-bridge converters.

Anbieter: buecher
Stand: 23.02.2020
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Investigating the Effect of Wind Load on Multi-...
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Investigating the Effect of Wind Load on Multi-Storey Building ab 49.9 EURO

Anbieter: ebook.de
Stand: 23.02.2020
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Folding Pods
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The quest for architectural space has most probably never been greater than in the present time. Architecture is created at the stake of space, which it encloses. Architectural structures which are temporary not used still enclose a precious amount of space. The aim of this publication is to test out the potential of deployable structures designed to encapsulate space when needed and to release space, when not in use, by employing folding mechanisms. The theoretical part will take a look at micro-architecture as a means of compressing and condensing functionality. Folding structures will be investigated in order to gain an understanding of different deployment mechanisms. Further, in the practical part the Kresling folding pattern will be tested in a design application aiming to translate the paper folding mechanism into material and load bearing structures with shape-shifting capacity. A small-scale capsule was designed - attached to an existing building, investigating the potential interaction with the built environment and as a modular configurable unit serving as a temporary living / working space in different locations.

Anbieter: Dodax
Stand: 23.02.2020
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Effect of Cold and Hot EGR on Engine Performanc...
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This book is an outcome of successful experimental investigating the impact of cold and hot exhaust gas recirculation (EGR) on engine performance and emissions. On euro-I C.I engine exhaust gas temperature, NOx, smoke, HC emissions, CO emission, CO2 emissions, efficiency, brake specific fuel consumption, and O2 were compared for hot and cold EGR as well as without EGR system at 4 different torques and 3 different speeds. Key Features: # Visual Display - The book has quite a number of pictures of the experimental set-up used for an easy understanding of the environment. # Emissions versus load. The impact has been discussed elaborately with the help of numerous graphs with actual readings.

Anbieter: Dodax
Stand: 23.02.2020
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Very Large Business Applications (VLBA): System...
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The role of IT’s use in business evolved over the past fifty years from isolated applications to integrated IT system landscapes. In this development, the focus and boundaries of business applications extended continuously. In order to consolidate research in this area, the term Very Large Business Applications (VLBA) was defined.A VLBA neither has geographical, nor organizational, nor cultural, nor technical limitations. Therefore, the integration aspect is essential to the successful operation of a VLBA. It can be implemented as business application(s) as well as system landscapes. As a VLBA supports at least one business process, changes in VLBAs lead to high financial, personnel and organizational costs, which clarify the strategic importance to the involved organization(s).The establishment of the research field VLBA is driven by the Otto von Guericke University Magdeburg and the Technische Universität München, where two Centers for Very Large Business Applications (CVLBA) were founded in 2006. These research facilities combine experience from a variety of disciplines including computer science, business administration, economics, psychology, library science and law in order to achieve synergy effects on research for VLBAs. The growing importance of this research area is evident by corresponding tracks and topics on multiple national and international conferences.As VLBAs are long-living and complex objects in organizations, research embraces their whole lifecycle. This includes planning new VLBAs, designing and implementing them as well as operational, tactical and strategical management of VLBAs. Especially the following topics are of interest for the Centers for VLBA.VLBA PlanningWhen planning the introduction of a new VLBA, the question arises, in which way a VLBA can be utilized effectively to support business processes. Current research focusses on information visibility in VLBAs for supply chains in its entirely, investigating its effect to strategic performance. In another project, challenges in the carve-out of VLBAs to face changing requirements are considered. Upcoming research will adapt concepts of VLBA for production industries to the provisioning of IT services.VLBA DesignDesign and Implementation of a VLBA extend classical software engineering. Advanced challenges are the management of the development process and the integration of VLBA components into each other and into the IT environment. One project investigates opportunities to integrate business simulations to VLBAs in order to enable customized business maneuvers. Another research project analyzes the role of IT for managing effective organizational controls.VLBA OperationEfficient and effective operation of a VLBA is crucial to an organization’s economic success. Research focusses on the minimization of resource-utilization without lowering the quality of a VLBA’s functionality. Current research in this field is performed on new requirements for load distribution in Cloud-VLBAs. Upcoming research will face the challenge to provide a closed loop for a Cloud Operations Management.VLBA ManagementOrganizations are facing continuous changes, e.g. in their own structure or because of the environment. To guarantee the successful support of business processes, VLBAs must face this challenge, too. Effective management of VLBAs should be supported by tools, methods and knowledge. Often costs and quality must be balanced against each other. One research project focuses on Software-as-a-Service-ERP-Solutions and gives recommendations for their implementation. Further research aims to support decisions by estimating non-functional properties of IT services provided by VLBAs. Current research is also engaged in investigating contract design and implications on performance of IT outsourcing projects.

Anbieter: Dodax
Stand: 23.02.2020
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