symmetric design
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Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 604
Author(s):  
Nayyar Iqbal ◽  
Jun Sang

Due to advancements in science and technology, software is constantly evolving. To adapt to newly demanded requirements in a piece of software, software components are modified or developed. Measuring software completeness has been a challenging task for software companies. The uncertain and imprecise intrinsic relationships within software components have been unaddressed by researchers during the validation process. In this study, we introduced a new fuzzy logic testing approach for measuring the completeness of software. We measured the fuzzy membership value for each software component by a fuzzy logic testing approach called the fuzzy test. For each software component, the system response was tested by identifying which software components in the system required changes. Based on the measured fuzzy membership values for each software component, software completeness was calculated. The introduced approach scales the software completeness between zero and one. A software component with a complete membership value indicates that the software component does not require any modification. A non-membership value specifies that the existing software component is no longer required in the system or that a new software component is required to replace it. The partial membership value specifies that the software component requires few new functionalities according to the new software requirements. Software with a partial membership value requires partial restructuring and design recovery of its components. Symmetric design of software components reduces the complexity in the restructuring of software during modification. In the study, we showed that by using the introduced approach, high-quality software that is faultless, reliable, easily maintained, efficient, and cost-effective can be developed.



2021 ◽  
Author(s):  
Nikunj Dudani ◽  
Satoshi Takahama

<p>It is important to characterize the composition of aerosol particles in air, which causes adverse health effects and millions of deaths each year. Aerosol, or particulate matter (PM), is difficult to characterize because of its wide range of particle sizes; constituents (various organic and inorganic compounds); concentration; morphology; state (liquid or solid); and time-dependent modification.<br>Infrared (IR) spectroscopy is a non-destructive method, which provides useful chemical information about the constituents. Current methods for collecting samples use filters that are made of materials which interferes with the IR spectra and thus lowers detection capabilities. Hence, collection on an IR-transparent substrate is desirable. In order to make a good quantitative measurement of the composition of the aerosol using IR-spectroscopy, a collector design should achieve some objectives. Low size-dependence, low chemical interference, and high collection efficiency are required to collect an aerosol sample that is identical to the aerosol in air. Furthermore, high spatial uniformity in deposition pattern is required to reduce optical artefacts or spectrometer dependence, and high collection mass flux is required to reduce the collection time needed for making a confident claim.<br>Electrostatic precipitation (ESP) is a versatile method of aerosol collection and does not suffer from high pressure drop (which can modify the aerosol chemical composition, for example in filtration), or from bounce-off effects (which preferentially samples the size range and liquids, for example in impaction). ESP devices for particle deposition are present in either a translationally symmetric design (linear system) or a radially symmetric design (radial system). Most ESP designs in the public domain have been designed for different purposes and face limitations for fulfilling objectives stated above. Hence, a new device is necessary to meet performance objectives.<br>Our design is based on an analytical, dimensionless (scalable) mathematical model that embodies the physics of particle migration trajectories due to fluid dynamics and electrostatics that lead to particle capture in a two-stage ESP device. This model allowed us to evaluate the tradeoffs among objectives to arrive at a design optimized across multiple objectives, and across multiple length scales (due to its dimensionless form). We validated this model against numerical simulations using COMSOL Multiphysics software, which is considered to be accurate but can only be run for a limited number of configurations (with respect to geometry and operating parameters) due to its high computational cost. Using the validated analytical model, we investigate the relationship among device geometry, methods of particle introduction, operational parameters, and deposited particle positions (which determines collection efficiency, uniformity, and size dependence), to arrive at a range of designs that meet design criteria.<br>We further report the fabrication of a suitable embodiment using 3D-printing while incorporating ease of operation and handling. Measurement capabilities and limits of the device using different laboratory-generated aerosol are reported.</p>



PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0247438
Author(s):  
Diana C. de Oliveira ◽  
David G. Owen ◽  
Shuang Qian ◽  
Naomi C. Green ◽  
Daniel M. Espino ◽  
...  

Central venous catheters are widely used in haemodialysis therapy, having to respect design requirements for appropriate performance. These are placed within the right atrium (RA); however, there is no prior computational study assessing different catheter designs while mimicking their native environment. Here, a computational fluid dynamics model of the RA, based on realistic geometry and transient physiological boundary conditions, was developed and validated. Symmetric, split and step catheter designs were virtually placed in the RA and their performance was evaluated by: assessing their interaction with the RA haemodynamic environment through prediction of flow vorticity and wall shear stress (WSS) magnitudes (1); and quantifying recirculation and tip shear stress (2). Haemodynamic predictions from our RA model showed good agreement with the literature. Catheter placement in the RA increased average vorticity, which could indicate alterations of normal blood flow, and altered WSS magnitudes and distribution, which could indicate changes in tissue mechanical properties. All designs had recirculation and elevated shear stress values, which can induce platelet activation and subsequently thrombosis. The symmetric design, however, had the lowest associated values (best performance), while step design catheters working in reverse mode were associated with worsened performance. Different tip placements also impacted on catheter performance. Our findings suggest that using a realistically anatomical RA model to study catheter performance and interaction with the haemodynamic environment is crucial, and that care needs to be given to correct tip placement within the RA for improved recirculation percentages and diminished shear stress values.



2020 ◽  
Vol 4 (4) ◽  
pp. 263-271
Author(s):  
Selda Çalkavur

Secret sharing has been a subject of study since 1979. In the secret sharing schemes there are some participants and a dealer. The dealer chooses a secret. The main principle is to distribute a secret amongst a group of participants. Each of whom is called a share of the secret. The secret can be retrieved by participants. Clearly the participants combine their shares to reach the secret. One of the secret sharing schemes is  threshold secret sharing scheme. A  threshold secret sharing scheme is a method of distribution of information among  participants such that  can recover the secret but  cannot. The coding theory has been an important role in the constructing of the secret sharing schemes. Since the code of a symmetric  design is a linear code, this study is about the multisecret-sharing schemes based on the dual code  of  code  of a symmetric  design. We construct a multisecret-sharing scheme Blakley’s construction of secret sharing schemes using the binary codes of the symmetric design. Our scheme is a threshold secret sharing scheme. The access structure of the scheme has been described and shows its connection to the dual code. Furthermore, the number of minimal access elements has been formulated under certain conditions. We explain the security of this scheme.



Author(s):  
Ashraf Yahya ◽  
Syed M. Usman Ali ◽  
Muhammad Farhan Khan

Purpose Multilevel inverter (MLI) is an established design approach for inverter applications in medium-voltage and high-voltage range of applications. An asymmetric design synthesizes multiple DC input voltage sources of unequal magnitudes to generate a high-quality staircase sinewave comprising a large number of steps or levels. However, the implications of using sources of unequal magnitudes results in the requirements of a large variety of inverter switches and higher magnitudes of the total blocking voltage (TBV) rating of the inverter, which increase the cost. The purpose of this study is to present a solution based on algorithms for establishing DC source magnitudes and other design parameters. Design/methodology/approach The approach used in this study is to develop algorithms that bring an asymmetric cascaded MLI (ACMLI) design close to symmetric design. This approach then reduces the variety of switch ratings and minimizes the TBV of the inverter. Thus, the benefits of both asymmetric design (generation of a large number of voltage levels in the output waveform) and symmetric design (modularity) are achieved. The proposed algorithms can be applied to a number of ACMLI topologies, including classical cascaded H-bridge (CHB). The effectiveness of the proposed algorithms is validated by simulation in Matlab-Simulink and experimental setup. Findings Two new algorithms are proposed that reduce the number of variety of switches to just three. The variety can further be reduced to two under a specified condition. The algorithms are compared with the existing ones, and the results are promising in minimizing the TBV rating of the inverter, which results in cost reduction as well. For a specific case of four CHBs, the proposed Algorithm-1 produced 27% and Algorithm-2 produced 53% higher levels. Moreover, the presented algorithms produced minimum values of the TBV and resulted in minimum cost of inverter. Originality/value The proposed algorithms are novel in structure and have achieved the targeted values of minimized switch variety and reduced TBV ratings. Due to less variety, the inverter achieves a near symmetric design, which enables to attain the added advantages of modularity and reduced difference of power sharing among the DC sources.



2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Ji S. Jung ◽  
Jung N. Lee ◽  
Joung M. Kim ◽  
Jong K. Park

A radio frequency identification reader antenna having multitag identification for medical systems is presented, which consists of four PIFAs, two hybrid couplers, and four power dividers. The high isolation is achieved by the symmetric design of the antenna geometry and four power dividers, which are fed by two hybrid couplers. The experimental results show an isolation of more than 40 dB in the North American (902–928 MHz), Korean (917–923.5 MHz), and Japanese (916.7–923.5 MHz) RFID frequency bands.



Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 327
Author(s):  
Boel Ekergård ◽  
Mats Leijon

Even though the magnetic circuit of a linear electric machine is very similar to a rotating electric machine, they diverge in one fundamental property. The linear generator is open in both ends, i.e., the magnetic circuit is non-symmetric. This paper investigates and discusses the drawbacks of this non-symmetric design in a linear permanent magnet generator, installed in a wave energy conversion system. A two-dimensional geometry has been utilized for the numerical calculations in a finite element method simulation tool. The results present an increased cogging force and significant core losses in the translator as consequences of the longitudinal ends in the machine.



2019 ◽  
Vol 9 (9) ◽  
pp. 1892 ◽  
Author(s):  
Hseng-Tsong Wang ◽  
Chi-Feng Chen ◽  
Sien Chi

A numerical solution for the broadband planar-lightwave-circuit (PLC) splitter with a variable splitting ratio based on asymmetric three waveguides weighted by the Blackman weighting function is designed for passive optical network applications with wavelengths between 1.53 and 1.57 µm. The performance of the proposed splitter is verified using the beam propagation method (BPM). It was found that a polynomial function of the splitting ratios accompanying a geometrical shift can be derived from the proposed splitter. The splitting ratio can be changed from 50:50 to 90:10 with this geometrical shift. The excess loss, crosstalk, polarization dependent loss, and splitting ratio variations against wavelength of the proposed splitter with wavelengths between 1.53 and 1.57 µm are better than 0.139 dB, −22.75 dB, 0.006 dB, and 0.335%, respectively. Obviously, the proposed splitter with variable splitting ratio retains the advantages of the symmetric design, such as low excess loss, low crosstalk, polarization insensitivity, broadband, and wavelength insensitivity.



2019 ◽  
Vol 43 (5) ◽  
pp. 2399-2406 ◽  
Author(s):  
Samira Akhbarifar ◽  
Hamid Haj Seyyed Javadi ◽  
Amir Masoud Rahmani ◽  
Mehdi Hosseinzadeh


2018 ◽  
Vol 2 (4) ◽  
pp. 1-4
Author(s):  
Guoqiang Wu ◽  
Geng Li Chua ◽  
Navab Singh ◽  
Yuandong Gu


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