Initial Design Parameters Research Articles

Improved thermodynamic design of organic radial-inflow turbine and ORC system thermal performance analysis

The Organic Rankine Cycle (ORC) has obvious advantages in the utilization of low-temperature heat source (80–300°C). Based on specific heat source, this paper determines design conditions of radial-inflow turbine with six kinds of dry working fluids. This paper presents a new method for modeling of ORC based on radial-inflow turbine with the novel selection of initial design parameters. In the selection procedure of the initial design parameters, the properties of organic working fluids should be taken into consideration to control the increase of υ2/υ1, which can lead to the large relative velocity ratio and the poor performance of the radial–inflow turbine. The study shows that the applicable selection area of initial design parameters differentiates from that recommended in the literature for organic working fluids. The lowest cycle ideal efficiency with R123 results in the minimums of the cycle thermal efficiency and the cycle net power, which reaches 8.33% and 67.24kW, respectively. Although the relative internal efficiency of the radial-inflow turbine with R600a is in the middle level, the highest cycle thermal efficiency and cycle net power reach 9.17% and 74.59kW, respectively. The results show that the ORC systems with R600 and R600a both have better cycle performance with smaller geometric dimensions and more excellent thermal matching with specific heat source.

Enhanced hybrid active tuned mass dampers for structures

Based on the recent research by Li and Cao in 2015, now taking the stroke mitigation as a target, the enhanced hybrid active tuned mass dampers (EHATMD) have been proposed in order to attenuate undesirable oscillations of structures under the ground acceleration. In accordance with the mode generalized system in the specific vibration mode being controlled (simply referred herein to as the structure) and continuing to make use of the negative normalized acceleration feedback gain factors scheme, the dynamic magnification factor (DMF) has been formulated for the structure furnished with an EHATMD. Then, the criterion for the optimum searching can be determined as the minimization of the minimum values of the maximum DMF (min.min.max.DMF). Employing the genetic algorithm, the effects of varying the key parameters on the optimum performance of EHATMD have been scrutinized in order to capture the expected performance. Furthermore, for a comparison, the optimum results of hybrid active tuned mass dampers (HATMD) with the same initial design parameters using both the genetic algorithm and negative normalized acceleration feedback gain factor scheme are also taken into consideration. Results of analysis have demonstrated that EHATMD outperforms HATMD and thereby may be regarded as a novel extension of HATMD.

Influence of Magnet Material Selection on the Design of Slow-Speed Permanent Magnet Synchronous Generators for Wind Applications

This paper analyses the influence of selected magnet materials on the design of slow-speed permanent magnet synchronous generators for use in wind applications. The design procedure, including setting of the initial design parameters of the machine, calculations of machine dimensions, magnetic flux in the air-gap, and electrical parameters as well as the selection criteria of permanent magnets for the use in the permanent magnet generator is presented. According to the calculations, a generator prototype is constructed with four different rotors, where different magnetic materials are used. The machine is tested using the different rotors and the influence of the different magnetic materials to the output characteristics of the machine is shown. The price to power analysis of the used magnetic materials is provided and conclusions for the possible machine design benefits and drawbacks are presented in the study. The investigations carried out show that NdFeB magnets are the preferred ones in terms of the performance and weight reduction, whereas there are considerable alternatives available, if the design and performance criteria are flexible. DOI: http://dx.doi.org/10.5755/j01.eie.23.1.17581

Biomechanical Response of Military Booted and Unbooted Foot-Ankle-Tibia from Vertical Loading.

A new anthropomorphic test device (ATD) is being developed by the US Army to be responsive to vertical loading during a vehicle underbody blast event. To obtain design parameters for the new ATD, a series of non-injurious tests were conducted to derive biofidelity response corridors for the foot-ankle complex under vertical loading. Isolated post mortem human surrogate (PMHS) lower leg specimens were tested with and without military boot and in different initial foot-ankle positions. Instrumentation included a six-axis load cell at the proximal end, three-axis accelerometers at proximal and distal tibia, and calcaneus, and strain gages. Average proximal tibia axial forces for a neutral-positioned foot were about 2 kN for a 4 m/s test, 4 kN for 6 m/s test and 6 kN for an 8 m/s test. The force time-to-peak values were from 3 to 5 msec and calcaneus acceleration rise times were 2 to 8 msec. Compared to the neutral posture, the "off-axis" measures (e.g. shear and bending moment) were much greater in magnitude in plantar- or dorsi-flexed posture. The results as a function of velocity demonstrated uniform increases with increasing test velocities. The response corridors supplied from the present investigation will serve as initial design parameters for the ATD lower leg, and can also be used for validation for a human computational model.

I/O System for A 77/154-GHz, 0.5-MW Dual Regime Gyrotron

This paper contributes to the design of a common input/output (I/O) system to support a dual regime gyrotron operation. I/O system comprises of different subassemblies such as magnetron injection gun (MIG), quasi-optical launcher, and RF window. The operating frequencies selected are 77/154 GHz with the desired mode-pair TE15,4/TE28,8, respectively. The necessary selection criteria of such unified design for these subassemblies has been briefly discussed. The initial design parameters have been selected using our in-house code Gyrotron Design Suite version 3.0 2014 (GDSv3.0 2014). Final optimization of MIG to generate electron beam with proper parameters to support the maximum power transfer has been carried out using a particle trajectory code ESRAY. A dimpled wall, helical cut launcher has been designed to convert the complex higher order modes to a simple Gaussian-like beam and has been optimized with a commercial software launcher optimization tool. The design and optimization of RF window has been done using GDSv3.0, which will allow the chosen frequency beam to be extracted out from the gyrotron.

Determination of energy to be supplied by photovoltaic systems for fan-pad systems in cooling process of greenhouses

Intending to increase the reliability of photovoltaic systems in agriculture sector, this work was developed to calculate the energy required by fan-pad systems for the cooling process in greenhouses. This calculation aims to ensure that the cooling process is completely sustainable. Today, there are no scientific tools to determine the electrical energy consumed by air exhaust fans. In order to address this problem, a mathematical model that predicts the greenhouse temperatures and ventilation rates, was calibrated with experimental data. The results correspond to a typical summer day with high solar radiation and showed that mathematical model can enhance the management of the energy for the cooling process. These results are: power of exhaust fans and their operating hours. It was used a methodology for selection of photovoltaic systems in order to design grid-connected configurations systems capable of producing, at least, the whole of the required energy by three greenhouses with different areas. It is concluded that the accuracy of the model is acceptable and with the methodology of selection of photovoltaic systems represent a reliable tool for calculus of electric power [W] and electric energy [kWh] consumed by the fans, which represent the main and initial design parameter of any type of photovoltaic system.

Design and analysis of a novel spoke‐type permanent magnet synchronous motor

This study presents a spoke-type permanent magnet synchronous motor (STPMSM) with a novel rotor which contains four individual iron core parts with flux barriers that are designed to realise a near-sinusoidal air gap flux density waveform. This novel type of rotor does not require thin bridges or retaining sleeves, the iron core parts of a rotor of this type are fixed to a non-magnetic sleeve by using dovetail slots, this structure can restrict flux leakage effectively and ensure sufficient mechanical strength. The initial design parameters of a 3 kW novel motor were obtained in the initial design process first, then several key parameters were optimised by using the Taguchi method, finally a comparative analysis of the novel motor structure and the conventional STPMSM structure was performed. The comparative analysis results reveal that the novel motor structure is superior to the conventional motor structure.

Wideband Four-Way Filtering Power Divider With Sharp Selectivity and Wide Stopband Using Looped Coupled-Line Structures

A compact wideband four-way filtering PD is presented. The structure of the proposed device includes a pair of looped coupled-line structures to provide the needed power division to four output ports. Moreover, a pair of short-ended coupled-line stubs is used to introduce multiple transmission poles and transmission zeros for a sharp cut-off of the passband and high upper-stopband rejection. A detailed design procedure is shown to determine the initial design parameters. A prototype is designed, simulated and measured experimentally. The measured results show 56.5% bandwidth centered at 1.5 GHz with more than 15 dB upper-stopband rejection up to 4.15 GHz, more than 13 dB in-band isolation, and 15 dB return loss at all output ports.

Design and analysis of annular combustion chamber of a low bypass turbofan engine in a jet trainer aircraft

The design of an annular combustion chamber in a gas turbine engine is the backbone of this paper. It is specifically designed for a low bypass turbofan engine in a jet trainer aircraft. The combustion chamber is positioned in between the compressor and turbine. It has to be designed based on the constant pressure, enthalpy addition process. The present methodology deals with the computation of the initial design parameters from benchmarking of real-time industry standards and arriving at optimized values. It is then studied for feasibility and finalized. Then the various dimensions of the combustor are calculated based on different empirical formulas. The air mass flow is then distributed across the zones of the combustor. The cooling requirement is met using the cooling holes. Finally the variations of parameters at different points are calculated. The whole combustion chamber is modeled using Siemens NX 8.0, a modeling software and presented. The model is then analyzed using various parameters at various stages and levels to determine the optimized design. The aerodynamic flow characteristics is simulated numerically by means of ANSYS 14.5 software suite. The air-fuel mixture, combustion-turbulence, thermal and cooling analysis is carried out. The analysis is performed at various scenarios and compared. The results are then presented in image outputs and graphs.

Impact risk assessment and planetary defense mission planning for asteroid 2015 PDC

In this paper, an integrated utilization of analytic keyhole theory, B-plane mapping, and planetary encounter geometry, augmented by direct numerical simulation, is shown to be useful in determining the impact risk of an asteroid with the Earth on a given encounter, as well on potential future encounters via keyhole passages. The accurate estimation of the impact probability of hazardous asteroids is extremely important for planetary defense mission planning. Asteroids in Earth resonant orbits are particularly troublesome because of the continuous threat they pose in the future. Based on the trajectories of the asteroid and the Earth, feasible mission trajectories can be found to mitigate the impact threat of hazardous asteroids. In order to try to ensure mission success, trajectories are judged based on initial and final mission design parameters that would make the mission easier to complete. Given the potential of a short-warning time scenario, a disruption mission considered in this paper occurs approximately one year prior to the anticipated impact date. Expanding upon the established theory, a computational method is developed to estimate the impact probability of the hazardous asteroid, in order to assess the likelihood of an event, and then investigate the fragmentation of the asteroid due to a disruption mission and analyze its effects on the current and future encounters of the fragments with Earth. A fictional asteroid, designated as 2015 PDC – created as an example asteroid risk exercise for the 2015 Planetary Defence Conference, is used as a reference target asteroid to demonstrate the effectiveness and applicability of computational tools being developed for impact risk assessment and planetary defense mission planning for a hazardous asteroid or comet.

The Development of a Pulsed Power Supply for μECM

Electrochemical Machining (ECM) is a well-established process in areas such as the aviation and automobile industries but the further commercial development and use of the μECM process has been prohibited by several issues, the main one being the lack of a suitable power supply unit (PSU) that can deliver the high-current pulses required while maintaining a minimal form factor, physical geometry, and realistic cost. The work presented in the paper is based on research that was carried out during the development of a novel switch mode power supply (SMPS) that is capable of delivering nano-second pulses at the MHz frequency range to the machine tool with minimal inductance. Preliminary experimental work was conducted to obtain initial design parameters and specifications required for the power supply. This included analysis of load characterisation followed by an investigation into the power switching using gallium nitrate based field effect transistors (FETs) as a novel switching technology and an investigation of the effects of the Inter Electrode Gap (IEG) loop. A Pulse Width Modulator (PWM) Frequency generator was constructed that was tested and shown to produce a modulated frequency of up to 45MHz with a minimum pulse on time of 14ns. Methods were investigated and deployed for monitoring the current and voltage sensing feedback for optimising process performance and control. Control system requirements were defined and implemented by adapting a Texas Instrument Piccolo microcontroller specifically for interfacing with the PSU that was then integrated with the higher-level Delta Tau control system deployed for the controlling the overall machining process of the μECM demonstrator machine. The PSU was tested, validated and integrated with the demonstrator machine for a number of machining trials that were conducted on copper and 18CrNi8, with material removal observed. This paper will outline the development work that was undertaken for the PSU and present findings from the PSU control tests. In addition, findings will also be discussed and presented from the analysis of a novel multi-probe IEG connection concept which was shown to be correctly transmitting pulses to the IEG with a total loop inductance of just 50 nH with pulse-on times as short as 50ns without any issue.

Case studies of geophysical imaging for road foundation design on soft soils and embankment risk assessment

Population growth along the coast of eastern Australia has increased demand for new and upgraded transport infrastructure within intervening coastal floodplains and steeper hinterland areas. This has created additional challenges for road foundation design.The floodplain areas in this region are underlain by considerable thicknesses of recently deposited alluvial and clayey marine sediments. If characterisation of these deposits is inadequate they can increase road construction costs and affect long-term road stability and serviceability. Case studies from a major coastal highway upgrade demonstrate how combining surface wave seismic and electrical geophysical imaging with conventional geotechnical testing enhances characterisation of these very soft and soft soils. The geophysical results also provide initial foundation design parameters such as void ratio and pre-consolidation pressure.A further significant risk issue for roads is potential embankment instability. This can occur during new road construction or when upgrades of existing embankments are required. Assessing the causes of instability of existing steeper embankments with drilling and probing is often difficult and costly due to access and safety problems. In these situations combinations of electrical, ground penetrating radar and P-wave seismic imaging technologies can rapidly provide information on the likely conditions below both the roadway and embankment. Case studies show the application of these technologies on two unstable road embankments.It is concluded that the application of both geophysical imaging and geotechnical testing is a cost-effective enhancement for site characterisation of soft soils and for risk assessment of potentially unstable embankments. This approach overcomes many of the current limitations of conventional methods of site investigation that provide point location data only. The incorporation of geophysics into a well crafted site investigation allows concentration on fewer but higher quality soil probings and geotechnical boreholes.

Design of Variable-Flux Permanent-Magnet Machines Using Alnico Magnets

This paper proposes a novel design for variable-flux machines with Alnico magnets. The proposed design uses tangentially magnetized magnets to achieve high air-gap flux density and to avoid demagnetization by the armature field. Barriers are also inserted in the rotor to limit the armature flux and to allow the machine to utilize both reluctance and magnet torque components. An analytical procedure is first applied to obtain the initial machine design parameters. Then, several modifications are applied to the stator and rotor designs through finite-element analysis (FEA) simulations to improve machine efficiency and torque density. A prototype of the proposed design is built, and the experimental results are in good correlation with the FEA simulations, confirming the validity of the proposed machine design concept.

Tunable band‐pass filter with wide stopband and high selectivity using centre‐loaded coupled structure

A tunable band-pass filter using a coupled structure that is centrally tapped with a resonator is proposed for wideband applications. The utilised resonator includes parallel-coupled lines loaded with a short-ended varactor. The resonator enables the independent tunability of two transmission zeroes (TZs), which define the passband of the filter. Moreover, the structure creates multiple TZs in upper stopband which enable realising a wide spurious-free stopband. A thorough theoretical analysis is used to verify the performance and calculate the initial design parameters. To validate the proposed design procedure, a prototype is designed, fabricated and tested. The simulated and measured results agree with the derived theory, and indicate a tuning range for the 3 dB bandwidth from 47.8 to 105.7% with, 1.4 dB of insertion loss and more than 12 dB of return loss. It also has more than 18 dB of attenuation across a stopband extending to around four times the centre frequency.

Optimum design of an off-grid hybrid renewable energy system for an office building

Although much attention has been paid to the utilization of hybrid renewable energy systems for either commercial buildings or residential ones, rare studies dealt with the application of off-grid hybrid renewable energy systems for commercial buildings. This paper presents a comprehensive study on the techno-economic performance of a stand-alone hybrid photovoltaic (PV)-wind-battery system for an office building located in Tehran, Iran. The Hybrid Optimization Model for Electric Renewables model was used to investigate the optimal design options and the techno-economic viability of the hybrid renewable energy system installed in that building. The proposed hybrid system based on renewable resources was designed to electrify the restrooms of the building. An optimal system configuration was chosen based on the total net present cost (NPC) and cost of energy (COE). The simulation results demonstrated that the optimum structure for the hybrid system for the primary load demand of 5.6 kW h per day, consists of 3 kW PV modules, 1 kW wind turbine, 1 kW inverter, and sixteen 200 A h batteries. The total NPC of such a system was estimated to be $21 132, while the COE was $1.543 per kW h. In addition, the proposed hybrid energy system could provide 2733 kW h additional electricity to the office building. Furthermore, in the last part of this research, a sensitivity analysis for different parameters such as primary load, wind speed, global solar radiation, interest rate, total NPC, cost of electricity, number of batteries and total electrical production was performed to demonstrate and elaborate the effect of each decision variable on the configuration of the optimum hybrid system. It became clear that two hybrid system configurations, i.e., PV-Wind-Battery and PV-Battery systems, are suggested as the most economical and feasible alternatives and have wide range of usage for different load demand values. Additionally based on the change in the initial design parameters such as wind speed, global solar radiation, load demand, and the real interest rate, a comparison between these two hybrid systems in terms of the total NPC, COE, electrical production, excess electricity, and grid extension distance has been made to investigate the effect of each decision variable on the optimal combination and the techno-economic viability of the hybrid renewable energy system.

Design of a double-anode magnetron-injection gun for the W-band gyrotron

A double-anode magnetron-injection gun (MIG) was designed. The MIG is for a W-band 10-kW gyrotron. Analytic equations based on adiabatic theory and angular momentum conservation were used to examine the initial design parameters such as the cathode angle, and the radius of the beam emitting surface. The MIG’s performances were predicted by using an electron trajectory code, the EGUN code. The beam spread of the axial velocity, Δvz/vz, obtained from the EGUN code was observed to be 1.34% at α = 1.3. The cathode edge emission and the thermal effect were modeled. The cathode edge emission was found to have a major effect on the velocity spread. The electron beam’s quality was significantly improved by affixing non-emissive cylinders to the cathode.

Bidirectional Evolutionary Structural Optimization (BESO) based design method for lattice structure to be fabricated by additive manufacturing

Unlike traditional manufacturing methods, additive manufacturing can produce parts with complex geometric structures without significant increases in fabrication time and cost. One application of additive manufacturing technologies is the fabrication of customized lattice-skin structures which can enhance performance of products while minimizing material or weight. In this paper, a novel design method for the creation of periodic lattice structures is proposed. In this method, Functional Volumes (FVs) and Functional Surfaces (FSs) are first determined based on an analysis of the functional requirements. FVs can be further decomposed into several sub-FVs. These sub-FVs can be divided into two types: FV with solid and FV with lattice. The initial design parameters of the lattice are selected based on the proposed guidelines. Based on these parameters, a kernel based lattice frame generation algorithm is used to generate lattice wireframes within the given FVs. At last, traditional bidirectional evolutionary structural optimization is modified to optimize distribution of lattice struts’ thickness. The design method proposed in this paper is validated through a case study, and provides an important foundation for the wide adoption of additive manufacturing technologies in the industry.

Establishment and validation for the theoretical model of the vehicle airbag

The current design and optimization of the occupant restraint system (ORS) are based on numerous actual tests and mathematic simulations. These two methods are overly time-consuming and complex for the concept design phase of the ORS, though they’re quite effective and accurate. Therefore, a fast and directive method of the design and optimization is needed in the concept design phase of the ORS. Since the airbag system is a crucial part of the ORS, in this paper, a theoretical model for the vehicle airbag is established in order to clarify the interaction between occupants and airbags, and further a fast design and optimization method of airbags in the concept design phase is made based on the proposed theoretical model. First, the theoretical expression of the simplified mechanical relationship between the airbag’s design parameters and the occupant response is developed based on classical mechanics, then the momentum theorem and the ideal gas state equation are adopted to illustrate the relationship between airbag’s design parameters and occupant response. By using MATLAB software, the iterative algorithm method and discrete variables are applied to the solution of the proposed theoretical model with a random input in a certain scope. And validations by MADYMO software prove the validity and accuracy of this theoretical model in two principal design parameters, the inflated gas mass and vent diameter, within a regular range. This research contributes to a deeper comprehension of the relation between occupants and airbags, further a fast design and optimization method for airbags’ principal parameters in the concept design phase, and provides the range of the airbag’s initial design parameters for the subsequent CAE simulations and actual tests.

철도 평면선형 개량시 설계초기조건이 미치는 영향

철도 선로선형은 한번 건설되면 변경하기가 매우 어렵다. 따라서 철도에서 선로선형의 변경은 일반적으로 큰 경제적비용을 수반한다. 본 연구에서는 기존 고속철도 및 일반철도의 속도향상을 위한 선형개량 시, 경제성을 고려한 평면선형의 허용개량범위 결정에 설계초기조건(교각)이 미치는 영향에 대해 분석하였다. 분석결과, 교각(Intersection Angle)이 클수록 직선부에 지장물이 있는 경우가 허용범위에 큰 영향을 미친다는 것을 알 수 있었다. 또한 교각이 클수록 최대 허용곡선반경은 작아지며, 허용완화곡선장은 길어짐을 알 수 있었다. 본 연구를 통해 교각의 크기 및 지장물 위치에 따른 개량허용범위를 쉽게 예상할 수 있으며, 속도향상 및 선로개선을 위한 선형 개량시 지장물을 고려한 경제적 설계가 가능할 것으로 예상된다. The alignment modifications after completion of railway construction entail a lot of efforts and time as well as high additional costs. In the process of renewal of the existing railway alignment to offer higher-speed services, the effect of initial design parameters(e.g., intersection angle) on determination of allowable degree of improvement of horizontal curves under consideration of economic efficiency is investigated in this study. From the analysis results, in the case that there are obstacles at the tangent line, it was found that the larger angle of intersection has a significant effect on the permissible zone. In addition, as the intersection angle is increased, the permissible values of maximum curve radius and the length of transition curve becomes smaller and longer, respectively. It is expected that this study can contribute to the efficient and accurate prediction of the permissible zone according to the locations of obstacles and the size of intersection angle as well as improvement in the railway alignment without any additional costs.

Direct design approach to calculate a two-surface lens with an entrance pupil for application in wide field-of-view imaging

In this work, a multifields optical design method aiming to calculate two high-order aspheric lens pro- files with an embedded entrance pupil is proposed. This direct design algorithm is capable of partially coupling more than three ray bundles that enter the same pupil with only two surfaces. Both infinite and finite conjugate objectives can be designed with this approach. Additional constraints such as surface continuity and smooth- ness are taken into account to calculate smooth and accurate surface contours described by point clouds. The calculated points are then fitted with rotationally symmetric functions commonly used in optical design tools. A presented subaperture sampling strategy that introduces a weighting function for different fields allows for a very well-balanced imaging performance over a wide field of view (FOV). As an example, a � 45 deg f ∕7.5 wide- angle objective is designed and analyzed to demonstrate the potential of this design method. It provides an excellent starting point for further optimization of the surfaces' coefficients and initial design parameters, result- ing in a very good and well-balanced imaging performance over the entire FOV. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original