TUBE DESIGN AND CIRCUIT CONSIDERATIONS FOR FAST-HEATING ELECTRONIC SYSTEMS

Crashworthiness design draws considerable attention and interest in energy absorption systems. An optimal design of circular stepped tubes based on free inversion is presented in the current work to improve and enhance the crashworthiness characteristics under axial impact loading. Circular tubes have been known to be efficient energy absorbers per unit weight, and may be considered as the main part of energy absorbing devices even for frequently impact operation like landing gear or for sudden accidents like other vehicles. The precise choice of the circular tubes' material, shape, and mechanism may save a person life or save a valuable equipment from damage. Adaptive Multiple-Objective Optimization (AMO) can obtain more light and efficient section. An optimization of variable parameters, which represent the shape of a stepped tube under axial impact, is performed using the platform of ANSYS-DESIGN-EXPLORATION linked with LSDYNA code. The analysis leads to 16% reducing in mass with corresponding 31% improving in energy absorption.

Introduction. X-ray inspection plays a unique role among all nondestructive testing methods for products and materials due to sufficiently high resolution and high penetrability. The present study is designed to consider the key features of microfocus X-ray sources, their areas of application, and main technical characteristics.Aim. The paper aims to systematize information and review modern X-ray radiation sources for the implementation of microfocus radiography.Materials and methods. The main designs of microfocus X-ray tubes (soldered and demountable) were considered relying on the experience of the St Petersburg State Electrotechnical University in developing and operating such equipment, as well as the experience and open-access publications of foreign researchers and developers. Data collected by leading research teams over the last ten years were analyzed.Results. The paper presents design features for each main type of microfocus X-ray tubes – soldered and demountable. All key structural elements are considered: an anode assembly, a cathode assembly, and a focusing system. The influence of anode target material on the X-ray tube radiation spectrum is shown. An original design of a liquid-anode microfocus X-ray tube is described to demonstrate its key features and advantages. In addition, the paper gives an overview of cathodes used in microfocus X-ray tubes (tungsten cathode and lanthanum hexaboride cathode), as well as providing a detailed description of calculations performed for focusing systems. Finally, the designs of modern X-ray tubes are presented.Conclusion. Modern X-ray tubes are high-tech products that allow for high-resolution research of various objects. The main advantage of testing performed with the use of X-ray tubes consists in high resolution (micron and submicron). The X-ray images of test objects used to determine their spatial resolution are given, which clearly illustrate the vast possibilities of this technology. In addition, ways to improve microfocus X-ray tubes are briefly discussed. The considered materials can be useful in selecting a nondestructive testing tool, as well as in developing and creating X-ray systems on the basis of microfocus X-ray tubes.

With the advancements in aircraft gas turbine engine technology over the past decade (in materials, structures, and analytical design methods) along with those anticipated for the next decade, there is renewed interest in the Mach 3.0 to 6.0 operating regime for both commercial transports and military weapon systems. The propulsion systems for these airplanes will in all probability be a function of the flight regime selected for a particular application; i.e., a turbofan engine for Mach<4.0, and a dual mode turboramjet for the Mach 4.0 to 6.0 aircraft. There are a number of component technologies that will have to be developed for the propulsion system before these applications can become a reality. This paper addresses some of the tasks that will have to be accomplished relative to one of those components: the exhaust nozzle system. Introduction The exhaust nozzle system is a unique component which requires integration with the airplane system components (engine, winglbody, inlet) as well as special design considerations for acoustics and off-design point operation in order to optimize the overall system performance. The design requirements for the exhaust system stem from two sources: the airplane and the engine (see Figure 1). Requirement 0 Airplane Sustained supersonic/subsonic operation Propulsion system integration Community noiw regulations Landing WeatherItiW brakes 0 Advanced engine technology Dual mode cycle High exhaust system temperature Figure 1. Factors Affecting Nozzle Design. EWct on nozzle Multiple design points. high WA,, and eiector nozzles Drag and propulsion system performance Acoustic design considerations Thrust reverser Bypau ducWvalw, variable area mixers, and secondary air systems Cooling/materia$ High exhaust system pressure ratios With reference to Figure 1, airplane performance and operational requirements have a direct impact on the exhaust system design. For example: sustained high Mach operation requires high nozzle area ratio capability for best efficiency with the nozzle possibly being an integral part of the airplane; for commercial transports, FAA noise regulations impact engine size and require noise ASIA8 excunion/seals/ st~ctures/~~1uaton suppression and treatment techniques; inletlengine airflow mismatching at transonic speeds may necessitate an ejector nozzle to reduce large spillage drags; and, landing operations may call for a thrust reverser for safety as well as prolonging the life of tires and brakes. Manager, Exhaust Systems & Installed Technology Member AIAA The engine cycle aerothermodynamic and operating characteristics also affect the nozzle design (reference Figure 1). For example: high nozzle pressure ratios again mean high area ratios for high performance; large changes in nozzle area ratio to optimize overall performance will more than likely result in nonaxisymmetric nozzles for Mach 4.0 to 6.0 applications; high tailpipe temperatures require more cooling air andlor different cooling schemes; high pressures in the nozzle will require innovative structural design approaches; and installed performance optimization may necessitate auxiliary air systems requiring ejector nozzles for performance optimization as well as for cooling. In addition, integration between the engine and aircraft companies will be absolutely essential in order to optimize the system (airplanelinletlenginelnozzle) installed performance. This paper will discuss some of the issues and design considerations for the Mach 4.0 to 6.0 aircraft with primary emphasis on turboramjet propulsion systems which utilize a common inlet and exhaust system for both operating modes. Some discussion relative to Mach 3f civil transports which utilize turbofan propulsion systems will also be included. Technical Discussion Expanded Airbreathing Propulsion Corridor The operating envelope for future high Mach aircraft is shown on Figure 2 compared to the regime for current aircraft (shaded area). The area of interest for this paper is Mach 2.5 to 6.0 where advanced technology turbofanlturbojet (Mach <4.0) and turboramjet (4.O<M<6.0) propulsion systems are being considered. The aircraft applications include military weapon systems for both defensive and offensive missions and commercial transports.

Resonant wireless power transfer offers high degree of freedom for the receiver positioning, but it also has higher restraints on the design of the receiver circuit. This paper discusses design considerations for the design of the receiver circuit for applications in mid-power range (10100 W) using resonant wireless power transfer system. Wireless power receiver circuit consists of three main sub-circuits: resonant tank, rectifier circuit and DC-DC converter. The impact of each sub-circuit is analyzed with respect to efficiency and overall performance of the receiver circuit. Results from the mathematical models and simulations are compared with measurements. The final design of the receiver circuit is implemented in LCD TV and evaluated through laboratory measurements.

The fourth fundamental passive circuit element - memristor, has received the increased attentions after a real device was demonstrated by HP Lab in 2008. The distinctive characteristic of a memristor to record the historical profile of the voltage/current through itself creates great potentials in highly integrated circuit and system design. Among all the proposed memristor structures, magnetic-based spintronic memristor becomes a promising technology for its simple structure and the compatibility to the traditional CMOS process. In this paper, we depict a compact model of the spintronic memristor based on the magnetic-domain-wall motion mechanism. Our model takes into account the variations of material parameters and fabrication process, which significantly affect the actual electrical characteristics of a memristor in nano-scale technologies. Furthermore, we present the applications of the compact model, analyze the effect of process variations on memristor electrical properties, and discuss the corresponding circuit design considerations. Our proposed compact model can be easily implemented in Verilog-A language, compatible to SPICE-based simulation, and beneficial to minimize the design margin of memristor-based circuit implementations.

This two-part paper reviews recent innovations in circuit design that have accelerated the miniaturization of sensor nodes. In this second part of the paper, we focus on key building blocks of miniaturized sensor nodes, such as data transceivers, energy harvesters, power management units, and digital logic circuits. System level design considerations are also discussed to provide guidelines for the design of a miniaturized system. As an example prototype design, a 2.7-cm3 global navigation satellite system (GNSS) logger is proposed. This paper includes a die-stacked sensor platform composed of an ARM cortex M0 processor, energy harvester, power management unit, solar cell, optical receiver, sensor layer, and RF transmitter that exploits the discussed design techniques for ultra-low power operation. The GNSS logger can store GNSS signals of >1 k positions on a single battery charging without additional energy harvesting.

High performance stabilized EO/IR surveillance and targeting systems are in demand for a wide variety of military, law enforcement, and commercial assets for land, sea, air, and space. Operating ranges, wavelengths, and angular resolution capabilities define the requirements for EO/IR optics and sensors, and line of sight stabilization. Many materials and design configurations are available for EO/IR pointing gimbals depending on trade-offs of size, weight, power (SWaP), performance, and cost. Space and high performance military aircraft applications are often driven toward expensive but exceptionally performing beryllium and aluminum beryllium components. Commercial applications often rely on aluminum and composite materials. Gimbal design considerations include achieving minimized mass and inertia simultaneous with demanding structural, thermal, optical, and scene stabilization requirements when operating in dynamic operational environments. Manufacturing considerations include precision lapping and honing of ball bearing interfaces, brazing, welding, and casting of complex aluminum and beryllium alloy structures, and molding of composite structures. Several notional and previously developed EO/IR gimbal platforms are profiled that exemplify applicable design and manufacturing technologies.

Displays for military vehicles have very distinct operational and cost requirements that differ from other military applications. These requirements demand that display suppliers to Army and Marine ground-environments provide low cost equipment that is capable of operation across environmental extremes. Inevitably, COTS components form the foundation of these “affordable” display solutions. This paper will outline the major display requirements and review the options that satisfy conflicting and difficult operational demands, using newly developed equipment as an example. Recently, a new supplier was selected for the Drivers Vision Enhancer (DVE) equipment, including the Display Control Module (DCM). The paper will outline the DVE and describe development of a new DCM solution. The DVE programme, with several thousand units presently in service and operational in conflicts such as “Operation Iraqi Freedom”, represents a critical balance between cost and performance. We shall describe design considerations that include selection of COTS sources, the need to minimise display modification; video interfaces, power interfaces, operator interfaces and new provisions to optimise displayed video content.

Chapter 7 - Energy efficiency enhancement and linear amplifications: An envelope-tracking (ET) approach

This paper investigates the design procedures and experimental testing of a low-damage brace equipped self-centering friction-based connection named Resilient Slip friction Joint (RSFJ). The brace energy dissipation and restoring force is provided by the damper component. Previous studies have shown that the damper ultimate compression strength might be jeopardized due to damper rotational flexibility, which might lead to premature elastic buckling of the brace. To address the issue, a concept of telescopic tubes was introduced to be put in parallel to the damper(s). The design of the telescopic tube requires a thorough framework that considers different possible failure loads and the collapse modes, so that the brace ultimate strength can be accurately estimated. Such a process tends to be more complex than the conventional Concentrically Braced Frames (CBFs), due to the non-continuity(ies) appearing as damper installation which may lead to possible plastic hinge formation in different locations of the brace. This study aims to employ second-order plastic analysis for the design of the damper-brace assembly. The proposed method is, is then validated with current international codes’ procedure and also with destructive tests on the self-centring brace specimens. Finally, the seismic design considerations including the design of the connections and protected members are discussed in this paper. The current procedure could also be recruited for other new emerging damper-braces as well.

nowadays, manufacturers of power management integrated circuits (PMICs) are producing devices that integrate many of the functional blocks required in power supplies in single tiny chips. This paper highlights the circuit design considerations as a part of highly integrated, high switching frequency (few MHz range) PMICs optimized to be fabricated using CMOS fabrication technologies. Moreover, the effect of parasitic elements associated with integration of the driver and the power MOSFET gate parasitic elements on the performance of an integrated buck converter and its effect on the switching time and loss in power MOSFETs have been investigated. Finally, a driver has been tested using spice simulations to validate the theory and then experimental results have been presented.

An offshore drilling system designed expressly for the unique environment of the Arctic must take into account many parameters. This paper discusses design considerations for a drillship intended for extended offshore operation in the Arctic areas. Discussion of environmental protection and safety features for icebreakers, shipping rules, and icebreaking capability are included. Introduction About 3 years ago it became apparent that the offshore oil potential in the Beaufort Sea and Canadian Arctic Islands areas was sufficient to give serious consideration to practically and economically providing a system capable of performing the needed exploratory drilling service. The practical approach was to use proven drilling techniques, systems, and equipment, proven drilling techniques, systems, and equipment, but to apply them to an environment not previously considered in their design, using imagination to accept opposing precepts to conceive a workable compromise. Economics dictate that the results must be reasonably capable of profitable application. A preference for ship-shaped units for exploratory drilling and the existing technology for breaking navigable ice channels with ships afforded a marriageable pair of disciplines. The only total unknown was how pair of disciplines. The only total unknown was how to maintain a drilling station in a slowly moving ice sheet. Design Considerations Combining a drillship with an icebreaker provided the basis for the design considerations (Fig. 1). Throughout the design of the vessel, safety was the over-riding criterion - safety not only for the personnel, vessel, and equipment, but also safety personnel, vessel, and equipment, but also safety in terms of environmental protection. The design evolved around considerations of environmental parameters such as climatic conditions and their parameters such as climatic conditions and their impact; crew, equipment, and vessel safety; regulatory parameters; and icebreaking and operational requirements. Environmental Parameters Experience with ship-shaped drilling vessels was a starting point for the design. This experience was adapted to the hostile climate of the Arctic. Where interfacing problems between the drillship and the icebreaker were encountered, the solution was normally an adaptation of drilling equipment or systems to the environment. The winters of the Beaufort Sea and Canadian Arctic Islands are long and severe. Although temperatures do not fall as far below zero as they do in the southern continental belt of the Arctic, the cold is persistent. The chill factor, coupled with the strong prevailing winds, makes this a very hostile region during the winter months. The long period of total darkness further complicates operations period of total darkness further complicates operations in the Arctic during this season. The summers in this area are cool and short. Cloudiness is prevalent along the coast because of the open water and abundant moisture, The clouds are always low and their formation lasts longer where open water and ice coexist. Snow occurs during every month of the year in the Beaufort Sea region. On the other hand, rain has never been recorded from October through May at most Arctic weather stations. During the summer months (June through September), rain accounts for more than 75 percent of the precipitation. The water equivalent of the mean annual precipitation is about 8 in., divided almost equally between rain and snow. JPT P. 433

Effect of peripheral nonuniform distribution of furnace heat flux on thermo-hydraulic characteristics and design of riser downcomer circuit of natural circulation boiler

The bootstrap gate driver circuits are widely used for bridge-arm-type high-current and high-power-density converters due to their low cost and compact structures. In high-current applications, improper bootstrap parameters and circuit design will cause start-up gate–source voltage oscillation, bridge-arm shoot-through, and gate–source voltage overshoot. Because of the lack of research and detailed model on the above three aspects in high-current applications, this article proposes a full-parameter model of the driver circuit through a detailed analysis of the driver circuit and summarizes a set of systematic design methods, which provides a reference for the parameters and circuit design of bootstrap gate driver for Si-based or GaN-based converters. This article will help tackle the challenges encountered in the bootstrap gate driver circuit design for high-current and high-power-density converters.

This study focuses on the possibility of modular multilevel converter (MMC) loss optimisation by modulation without any additional circuit, where a common‐mode voltage is injected into a nearest level modulator. Owing to the common‐mode voltage injection, the proposed modulation strategy increases the fundamental voltage. Therefore, for a given voltage, operation is possible with the submodule (SM) voltage of at least one SM inserted each arm. This reduces the number of SMs required, resulting in reduction of conduction losses and leading to significant cost savings and/or returns on investment for facilities. Furthermore, the injection of common‐mode voltage also decreases the total SM transitions, resulting in reduction of switching losses. The proposed modulation strategy is valid under both normal and unbalanced ac fault conditions for MMCs. The common‐mode voltage extraction method is provided and its harmonic components are extracted. Then, the SM saving capability of the injection‐based nearest level modulation is discussed and the SM saving limit is presented in relation with modulation indexes. The optimisation of both conduction losses and switching losses is analysed. The effectiveness of the proposed modulation strategy under both normal and unbalanced ac fault condition is verified by simulations of a 101‐level three‐phase MMC in MATLAB/Simulink.