InAlGaN/GaN with AlGaN back-barrier HEMT technology on SiC for Ka-band applications

2017 ◽  
Vol 10 (1) ◽  
pp. 39-46
Author(s):  
Stéphane Piotrowicz ◽  
Jean-Claude Jacquet ◽  
Piero Gamarra ◽  
Olivier Patard ◽  
Christian Dua ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Positive Impact ◽  
Operating Conditions ◽  
Current Gain ◽  
Power Measurements ◽  
Aided Design ◽  
Load Pull ◽  
Buffer Structure ◽  
A Current ◽  
Improved Characteristics

This paper presents performances achieved with InAlGaN/GaN HEMTs with 0.15 µm gate length on SiC substrate. Technology Computer Aided Design simulations were used to optimize the heterostructure. Special attention was paid to the design of the buffer structure. I-V measurements with DC and pulsed bias voltages were performed. CW measurements at millimeter waves were also carried out and are detailed in the following sections. The technology, optimized for power applications up to 45 GHz, demonstrates a current gain cut-off frequency FTof 70 GHz and a maximum available gain cut-off frequency FMAGof 140 GHz. CW Load-pull power measurements at 30 GHz enable to achieve a maximum PAE of 41% associated with an output power density of 3.5 W/mm when biased at VDS= 20 V. These devices, with an improved buffer structure show, reduced recovery time in pulsed operating conditions. These improved characteristics should have a positive impact for pulsed or modulated signal applications.

CAD Of Anticorrosive Protection Of Steel Structures

2019 ◽  
pp. 18-23
Keyword(s):  
Protective Coating ◽  
Computer Aided Design ◽  
Steel Structures ◽  
Cost Effective ◽  
Operating Conditions ◽  
Computational Tool ◽  
Protection Method ◽  
Cost Effective Method ◽  
The Cost ◽  
Aided Design

The choice of cost-effective method of anticorrosive protection of steel structures is an urgent and time consuming task, considering the significant number of protection ways, differing from each other in the complex of technological, physical, chemical and economic characteristics. To reduce the complexity of solving this problem, the author proposes a computational tool that can be considered as a subsystem of computer-aided design and used at the stage of variant and detailed design of steel structures. As a criterion of the effectiveness of the anti-corrosion protection method, the cost of the protective coating during the service life is accepted. The analysis of existing methods of steel protection against corrosion is performed, the possibility of their use for the protection of the most common steel structures is established, as well as the estimated period of effective operation of the coating. The developed computational tool makes it possible to choose the best method of protection of steel structures against corrosion, taking into account the operating conditions of the protected structure and the possibility of using a protective coating.

ANALYSIS AND RESEARCH OF ADJUSTABILITY OF EQUIPMENT FOR INTERNAL SMALL-SIZED THREADING

2021 ◽  
Vol 2 ◽  
pp. 93-99
Author(s):  
A.O. KHARCHENKO ◽  
A.A. KHARCHENKO
Keyword(s):  
Flexible Manufacturing ◽  
Computer Aided Design ◽  
Transition Probabilities ◽  
Objective Assessment ◽  
Complete Information ◽  
Operating Conditions ◽  
Theoretical Research ◽  
Automated Production ◽  
Processing Modes ◽  
Aided Design

The article presents the results of analysis and theoretical research in the direction of improving equipment for internal threading of parts in a flexible automated production. Methods for assessing the flexibility and readjustability of equipment are considered, which can be used as the basis for the developed methodology for the synthesis of technological elements of modules in conditions of computer-aided design. It is proposed to consider the technological system of the flexible manufacturing module (FMM) of threading, as a system in which transitions from state to state occur under the action of the simplest flows with the parameters of the transition probabilities of a continuous Markov chain. The developed mathematical model, which describes the states of a FMM, taking into account the readjustment of its technological elements, makes it possible to reflect the influence on the operation of the module of the parameters of applications for the changeover of processing modes, a tool, a power threading head, basic elements of a machine tool, a device, a loading device. The structure of the model and the labeled graph of the states of the system can be improved as the number of parameters and characteristics is refined. The solution of the resulting system of equations of final probabilities using the normalization condition allows for given (or experimentally obtained) intensities of arrival and service of changeover requests for FMM of threading, to obtain the values of the probability of non-changeover operation, as well as the probabilities of finding the system in an inoperative state due to the corresponding changeovers. For complete information and an objective assessment of the preferred option for use in FMS conditions, it is also necessary to take into account the stochastic processes occurring in the system under real operating conditions.

CAD in the CIM Environment: Where Do We Go From Here?

1986 ◽  
Vol 39 (9) ◽  
pp. 1345-1349 ◽  
Author(s):  
Dell K. Allen ◽  
W. Van Twelves
Keyword(s):  
Computer Aided Design ◽  
Material Selection ◽  
Operating Conditions ◽  
Computer Integrated Manufacturing ◽  
Accurate Information ◽  
Functional Requirements ◽  
Essential Information ◽  
Design Systems ◽  
Aided Design ◽  
Product Definition

The importance of computer-aided design (CAD) has not been fully appreciated as it relates to computer integrated manufacturing (CIM). The CAD product definition model can provide essential information for many down-stream production, estimating, tooling, and quality assurance functions in the CIM environment. However, the product definition model may be inaccurate or incomplete, thus causing incomplete communication with possible scrap, re-work, and missed production deadlines. Other problems are related to the fact that many of our expert designers are retiring and taking their expertise with them. Merely being able to make 2D or 3D drawings on a CAD workstation does not make its operator a designer. A knowledge of production processes, tolerances, surface finish, and material selection is needed to supplement a designers knowledge of user needs, product functional requirements, operating conditions, cost, quality, and reliability targets. One of the most promising methods for providing timely and accurate information to the designer on an “as-needed” basis is through the use of expert design systems. Such systems promise to bridge the knowledge gap between CAD and CAM and help to incorporate these functions into the overall CIM environment.

scholarly journals Removal of Methylene Blue by Activated Glass Foams with TiO2 in Dark and Simulated Solar Light

2019 ◽  
Vol 61 (1) ◽  
pp. 33-43
Author(s):  
Florina Stefania Rus ◽  
Stefan Danica Novaconi ◽  
Paulina Vlazan ◽  
Madalina Ivanovici
Keyword(s):  
Energy Balance ◽  
Silicon Germanium ◽  
Computer Aided Design ◽  
Current Gain ◽  
Balance Model ◽  
Drift Diffusion ◽  
Simulated Solar Light ◽  
Oscillation Frequencies ◽  
Aided Design ◽  
Dc Current

AbstractThe effect of germanium trapezoidal profile shape on the direct current (DC) current gain (βF), cut-off frequency (fT) and maximum oscillation frequency (fMAX) of silicon-germanium (SiGe) hetero-junction bipolar transistors (HBTs) has been investigated. The energy balance (EB), hydrodynamic (HD) and drift-diffusion (DD) physical transport models in SILVACO technology computer aided design (T-CAD) simulator were used. It was found that the current gain values using energy balance model are higher than hydrodynamic and much higher than those corresponding to drift-diffusion. Moreover, decreasing the germanium gradient slope towards the collector side of the base enhances the maximum oscillation frequencies using HD and EB models whilst, they remain stable for DD model.

scholarly journals Incremental Automatic Correction for Digital VLSI Circuits

2020 ◽  
Author(s):  
Lamya Gaber ◽  
Aziza I. Hussein ◽  
Mohammed Moness
Keyword(s):  
Computer Aided Design ◽  
High Speed ◽  
Negative Impact ◽  
Positive Impact ◽  
Vlsi Circuits ◽  
Digital Vlsi ◽  
Large Numbers ◽  
Aided Design ◽  
The Impact ◽  
Compact Test

The impact of the recent exponential increase in complexity of digital VLSI circuits has heavily affected verification methodologies. Many advances toward verification and debugging techniques of digital VLSI circuits have relied on Computer Aided Design (CAD). Existing techniques are highly dependent on specialized test patterns with specific numbers increased by the rising complexity of VLSI circuits. A second problem arises in the form of large sizes of injecting circuits for correction and large number of SAT solver calls with a negative impact on the resultant running time. Three goals arise: first, diminishing dependence on a given test pattern by incrementally generating compact test patterns corresponding to design errors during the rectification process. Second, to reduce the size of in-circuit mutation circuit for error-fixing process. Finally, distribution of test patterns can be performed in parallel with a positive impact on digital VLSI circuits with large numbers of inputs and outputs. The experimental results illustrate that the proposed incremental correction algorithm can fix design bugs of type gate replacements in several digital VLSI circuits from ISCAS'85 with high speed and full accuracy. The speed of proposed Auto-correction mechanism outperforms the latest existing methods around 4.8x using ISCAS'85 benchmarks. The parallel distribution of test patterns on digital VLSI circuits during generating new compact test patterns achieves speed around 1.2x compared to latest methods.

scholarly journals Comparison between Occlusal Errors of Single Posterior Crowns Adjusted Using Patient Specific Motion or Conventional Methods

2020 ◽  
Vol 10 (24) ◽  
pp. 9140
Author(s):  
Ye-Chan Lee ◽  
Chunui Lee ◽  
June-Sung Shim ◽  
Ji-Man Park ◽  
Yooseok Shin ◽  
...  
Keyword(s):  
Digital Technology ◽  
Computer Aided Design ◽  
Occlusal Surface ◽  
Patient Specific ◽  
Average Deviation ◽  
Occlusal Surfaces ◽  
Conventional Methods ◽  
Map Analysis ◽  
Aided Design ◽  
A Current

Recently, digital technology has been used in dentistry to enhance accuracy and to reduce operative time. Due to advances in digital technology, the integration of individual mandibular motion into the mapping of the occlusal surface is being attempted. The Patient Specific Motion (PSM) is one such method. However, it is not clear whether the occlusal design that is adjusted using PSM could clinically show reduced occlusal error compared to conventional methods based on static occlusion. In this clinical comparative study including fifteen patients with a single posterior zirconia crown treatment, the occlusal surface after a clinical adjustment was compared to no adjustment (NA; design based on static occlusion), PSM (adjusted using PSM), and adjustment using a semi-adjustable articulator (SA) for the assessment of occlusal error. The root mean square (RMS; μm), average deviation value (±AVG; μm), and proportion inside the tolerance (in Tol; %) were calculated using the entire, subdivided occlusal surface and the out of tolerance area. Using a one-way ANOVA, the RMS and +AVG from the out of tolerance area showed a statistical difference between PSM (202.3 ± 39.8 for RMS, 173.1 ± 31.3 for +AVG) and NA (257.0 ± 73.9 for RMS, 210.9 ± 48.6 for +AVG). For the entire and subdivided occlusal surfaces, there were no significant differences. In the color-coded map analysis, PSM demonstrated a reduced occlusal error compared to NA. In conclusion, adjustment occlusal design using PSM is a simple and effective method for reducing occlusal errors that are difficult to identify in a current computer-aided design (CAD) workflow with static occlusion.

scholarly journals Computer-aided design system for vibration-frequency density meters

2021 ◽  
pp. 33-39
Author(s):  
Olga Oliynyk ◽  
Yurі Taranenko
Keyword(s):  
Vibration Frequency ◽  
Computer Aided Design ◽  
Free Vibrations ◽  
Operating Conditions ◽  
Design System ◽  
Bending Vibrations ◽  
Software Complex ◽  
Wide Range ◽  
Computer Aided ◽  
Aided Design

The article is devoted to the description of the developed automated design system for vibration-frequency density meters with a demonstration of the wide functionality of the program and interface settings. The development solves the problem of designing vibration-frequency density meters, calculating the quality factor and sensitivity of resonators, which provide the dependence of the frequency of self-oscillations on the controlled density. The lack of clear methodological recommendations for calibration, correction techniques for different methods of mounting the resonator significantly limits the use of vibration-frequency density meters, since the tasks set require special skills, competencies of both developers and personnel during operation. The algorithm of the developed software package is based on the calculation of the amplitude-frequency characteristics of a tubular resonator using a differential equation to determine the frequencies and forms of bending vibrations of a tubular resonator. The software implementation of the developed calculation model makes it possible not only to visualize the shapes, frequency, antinodes and vibration nodes of a tubular resonator of any design and a wide range of materials, but also takes into account the type of fastening, the numerical value of the support stiffness, makes it possible to adjust the placement of supports that meets the operating conditions while visualizing the shapes oscillations, simulate the distribution of sensitivity along the entire measurement range. The developed computer-aided design system has a simple and clear interface, and the absence of the necessary software installation and settings makes the product more accessible in the industrial environment of small enterprises. When using a subroutine for the numerical solution of the equation of free vibrations of a string, the software complex can be used to design string mechanical resonators of vibration-frequency sensors.   Keywords: vibration-frequency density meter; resonator; amplitude and frequency of oscillations; fixing conditions; antinode; sensitivity

scholarly journals Three-Level Inverter Control Techniques: Design, Analysis, and Comparisons

2021 ◽  
Vol 27 (3) ◽  
pp. 26-37
Author(s):  
Dan Selisteanu ◽  
Monica Roman ◽  
Lucian Mandache ◽  
Razvan Prejbeanu ◽  
Sergiu Ivanov ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Asynchronous Motor ◽  
Quality Criteria ◽  
Operating Conditions ◽  
Design Tools ◽  
Analysis And Design ◽  
Control Techniques ◽  
Linear Load ◽  
Computer Aided ◽  
Aided Design

This work addresses the analysis and design of various Proportional-Integral-Derivative (PID) control techniques for a three-level inverter. Multilevel power converters are modern and basic elements of high-voltage electric drive and power supply systems. By using simulations and specific computer-aided design tools, the overall functional characteristics of multilevel converters, as well as the electrical demands of the components, can be accurately assessed to obtain an appropriate control solution. An innovative and detailed software model of a three-level inverter is developed and then used for the implementation of control techniques. Several tuning methods are used to tune PID controllers for two specific cases: the multilevel inverter with a linear load and with an asynchronous motor load, respectively. A detailed analysis and comparisons of the quality criteria and control performance are achieved. This analysis shows that the choice of controller type depends on the inverter load. For the linear load, proper results are obtained with a PI Nichols-tuned controller, and for the asynchronous load, with a PI controller tuned via a modified Hokushin method. The computer-aided design tools can be further used for the simulation of the equipment in various operating conditions, normal and fault, following all functional parameters.

scholarly journals Germanium Gradient Optimization for High-Speed Silicon Germanium Hetero-Junction Bipolar Transistors

2019 ◽  
Vol 61 (1) ◽  
pp. 22-32
Author(s):  
Abdelkader Khadir ◽  
Nouredine Sengouga ◽  
Mohamed Kamel Abdelhafidi
Keyword(s):  
Energy Balance ◽  
Silicon Germanium ◽  
Computer Aided Design ◽  
High Speed ◽  
Bipolar Transistors ◽  
Current Gain ◽  
Balance Model ◽  
Drift Diffusion ◽  
Oscillation Frequencies ◽  
Aided Design

AbstractThe effect of germanium trapezoidal profile shape on the direct current (DC) current gain (βF), cut-off frequency (fT) and maximum oscillation frequency (fMAX) of silicon-germanium (SiGe) hetero-junction bipolar transistors (HBTs) has been investigated. The energy balance (EB), hydrodynamic (HD) and drift-diffusion (DD) physical transport models in SILVACO technology computer aided design (T-CAD) simulator were used. It was found that the current gain values using energy balance model are higher than hydrodynamic and much higher than those corresponding to drift-diffusion. Moreover, decreasing the germanium gradient slope towards the collector side of the base enhances the maximum oscillation frequencies using HD and EB models whilst, they remain stable for DD model.

Dynamic Analysis Step-by-Step

1998 ◽  
Vol 120 (08) ◽  
pp. 61-62
Author(s):  
Yi Sug Kwon
Keyword(s):  
Dynamic Analysis ◽  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Rigid Bodies ◽  
Operating Conditions ◽  
Industrial Systems ◽  
High Rise ◽  
Front End ◽  
Design Software ◽  
Aided Design

This article discusses about engineers who are relying on mechanical simulations to improve their understanding of loading and operating conditions with high-rise escalators gain in popularity. To model an escalator design’s steps for dynamic analysis, LG engineers simplified the mechanical system by applying the drive directly to the upper terminal gear and the driving pulley without the motor. To model an escalator’s continuous elastic handrail, LG engineers divided it into 127 discrete rigid bodies, resulting in a total of 381 independent degrees of freedom. Two friction contact elements for each handrail body are applied to prevent rotational motion of the handrail. LG Industrial Systems managers decided to expand the number of engineers at the company with access to the simulation model. They assigned LG engineers to work with Computer Aided Design Software, Inc. (CADSI), of Coralville, Iowa analysts to develop a front end to DADS that simplifies the process of developing a custom escalator model.

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