Parametric Modeling and Formability Study of Pipe Bending Without Mandrel Based on ABAQUS Secondary Development

Goal. The purpose of this computer modeling study is to validate the feasibility of a home monitoring system for wrist bone mineral density (BMD) measurement which is based on the parametric electrical impedance tomography (pEIT) method. Methods. A solution to the forward problem of the developing potential around the wrist due to current injection was developed using a Matlab numerical simulation of an adult computer human phantom. The backward problem is solved by building a lookup table of different bone densities which represent different disease stages. Results. The real part of the complex potential exhibits an average change of 30.7%–12% (between the most sensitive and the least sensitive electrodes) per BMD decrease of 23%. A 2 times higher sensitivity to a deterioration of the cortical bone than of the trabecular bone alone was found. A signal to noise ratio (SNR) level above 30 dB is required for a maximal performance of the system. The robustness to a deposition of the electrodes array in different directions is limited. Conclusion. It was found that the cortical BMD changes govern the model. The required SNR level is within the specs of similar systems. In a real device, the issue of sensors repositioning should be addressed. The proposed pEIT system makes self-monitoring of wrist BMD possible. It brings an added-value by enabling the monitoring of BMD between treatments and between traditional DEXA screenings.

Energy conservation and efficiency is an essential area of focus in contemporary building design. The perception that the designers of buildings during the Modernist period of architecture ignored these principles is a false one. The present study, an examination of Paul Rudolph’s Milam Residence, a masterpiece of American residential architecture, is part of a larger project endeavoring to create a knowledge base of the environmental performance of iconic modernist homes. A critical examination of the Milam House allows insight into specific design characteristics that impact energy efficiency and conservation. Located in Ponte Vedra Beach, Florida, the Milam Residence was constructed in 1962. It was the last of a series of Florida residences designed by Rudolph, Chairman of the Department of Architecture at Yale University (1958–1965). The structure’s form is strongly related to its location on a subtropical beachfront. This paper presents a detailed analysis of the building’s solar responsiveness. Specifically, we examine design strategies such as orientation and sunscreening and their effect on daylighting, shading, and heat gain. The analysis is based on parametric energy modeling studies using Autodesk’s Ecotect, an environmental analysis tool that allows simulation of building performance. While the initial target of the program was early design, the program allows the input of complex geometries and detailed programming of zones, materials, schedules, etc. The program's excellent analyses of desired parameters are augmented by visualizations that make it especially valuable in communicating results. Our findings suggest that the building, as built and situated on the site, does take advantage of daylighting and solar shading and does so in both expected and unexpected ways.

Design Directions for Composite Catalytic Hollow Fibre Membranes for Condensation Reactions

Preliminary study of the impact of urban greenery types on energy consumption of building at a district scale: Academic study on a canyon street in Nantes (France) weather conditions

This paper presents analytical modeling results for a triaxial frequency-domain electromagnetic-induction (EMI) sensor over a homogeneous earth containing a long linear conductor. Although the conductor studied is intended to represent an underground wire or pipe, it can represent any subsurface, linear geologic structure that can channel current. Treating the sensor transmitter as a vertical magnetic dipole, the model combines the well-known solution for the magnetic field arising from the interaction with the earth with the solution for the induced magnetic field from the excited subsurface conductor. Expressions for the three components of the magnetic field at an arbitrary point above the earth are presented. Two types of coupled, moving transmitter-receiver configurations (coaxial and coplanar) wereconsidered, and the model is sufficiently flexible to allow for many other sensor variations to be studied. Characteristics of the sensor signals were explored through several parametric modeling studies that demonstrate the sensitivity of the signals to transmitter frequency, earth conductivity, conductor depth, sensor geometry, and crossing angle. Using simple relationships developed from analysis of the sensor signals, key parameters such as conductor depth and orientation can be estimated. The ability of the model to predict and characterize sensor output should prove helpful in distinguishing between geologic features and man-made underground infrastructure. These modeling results also are expected to facilitate frequency-domain EMI data analysis and interpretation, sensor design and operation, and the development of detection and classification algorithms.

Data-driven collapse strength modelling for the screen pipes with internal corrosion defect based on finite element analysis and tree-based machine learning

PurposeThe purpose of this study is to investigate the effects of stud height, stud diameter, ultimate stress of stud and concrete strength on the static behaviour of studs in push-off tests based on the ductile fracture theory.Design/methodology/approachPush-off tests of headed stud shear connectors with different heights and diameters used in concrete of various strengths were designed and implemented. A finite element model was established based on a ductile fracture criterion of ML15 cold-heading steel with stress triaxiality and Lode angle parameter. Based on the results of the parametric study of the numerical model, equations were proposed to evaluate the effect of stud height hs, stud area As, concrete strength fc and stud ultimate strength fsu used in concrete of various strengths on the static behaviour of studs.FindingsThe typical failure phenomenon observed among the test specimens was the fracture of the shank of studs. The microscopic images of the stud fracture surfaces and the verified finite element model indicate that the studs were fractured as a result of the combined action of tension and shear.Originality/valueA new method for calculating ultimate load Pu and ultimate slip Su is proposed in this paper. In the method, Pu is linearly related to fsu0.2143, As0.7790, hs0.0974, fc0.2065. Su is linearly related to fsu1.078, As0.4681, hs(−0.3135), fc(−0.3480).

Solid foams are porous, monolithic materials with higher specific surface areas than the random packings that are commonly used in amine-based CO2 capture processes. In this work, the hydrodynamic characteristics (e.g., pressure drop, flooding point, and liquid holdup) and CO2 absorption performance of α-Al2O3 ceramic foam packings of different porosities were investigated experimentally in a gas–liquid countercurrent column. With a 30 wt % diglycolamine (DGA) solvent as the CO2 absorbent, the foams allowed higher flow rates of gas and liquid than a random packing before undesirable flooding was reached. Ceramic foams with lower porosities have larger operating capacities than those with higher porosities. A parametric study of a one-dimensional flow model was performed by investigating the effects of gas velocity, liquid velocity, and CO2 solvent loading on the CO2 removal performance. Lower gas velocities and higher liquid velocities increased the CO2 removal efficiency. The CO2 removal efficiency decre...

This chapter presents the design and parametric study of the multibody dynamic model of Retractable rod Vortex Generator (RrVG). RrVG is a retractable rod whose task is to generate vortices at the right time. The structure of the model is based on real electromechanical components (actuators). The design and simulations of the model have been carried out using the LMS/Siemens software. The complex system and description of the mechanical components are presented. The AMESim software was used to design and optimize the control system. A three-dimensional model of the mechanical system, worked out in VL software, allowed the kinematic and dynamic analysis for the required motion pattern. Three different positions relative to the reference system were investigated. The simulation results have revealed that the proposed design should operate properly. The rod which generates the vortex moves in a timely manner in relation to the time of vortex generation and the movement of the helicopter rotor blade on which it is installed.

Parametric study of the computational model on fuel and fission products characteristics analysis of HTR-PM equilibrium core

Validation and parametric study of FFRD model in DRACCAR code

Parametric study of the Two-Temperature Model for Molecular Dynamics simulations of collisions cascades in Si and Ge

An optimized design of a matrix treatment involves fluid selection and acidizing simulations to predict the outcome of the treatment; Many matrix acidizing treatment designs and fluid selections have been successfully accomplished by utilizing expert system technology. However, none of these present a complete and optimized result (i.e., by utilizing the output of the expert system to predict the acidizing outcome using an acidizing numerical simulator). In the meantime, several acidizing computer simulation studies have been conducted separately. This paper presents a study which integrates the treatment design, particularly the fluid selection process, and acidizing simulation for sandstone formations. Required parameters for sandstone acidizing such as acid type, concentration, volume, and injection rate/pressure are first selected using an expert system. The output from the expert system is further used for the input to an acidizing numerical simulator (UTACID). A new sandstone acidizing reaction model, appropriate for a high-temperature environment, and anisotropic medium have been implemented into UTACID to enhance the performance of the simulator. The expert system and the simulator have been integrated to provide an optimization tool for sandstone acidizing treatment design and simulation.

BackgroundDevelopment of an effective antiviral drug for Coronavirus Disease 2019 (COVID-19) is a global health priority. Although several candidate drugs have been identified through in vitro and in vivo models, consistent and compelling evidence from clinical studies is limited. The lack of evidence from clinical trials may stem in part from the imperfect design of the trials. We investigated how clinical trials for antivirals need to be designed, especially focusing on the sample size in randomized controlled trials.Methods and findingsA modeling study was conducted to help understand the reasons behind inconsistent clinical trial findings and to design better clinical trials. We first analyzed longitudinal viral load data for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) without antiviral treatment by use of a within-host virus dynamics model. The fitted viral load was categorized into 3 different groups by a clustering approach. Comparison of the estimated parameters showed that the 3 distinct groups were characterized by different virus decay rates (p-value < 0.001). The mean decay rates were 1.17 d−1 (95% CI: 1.06 to 1.27 d−1), 0.777 d−1 (0.716 to 0.838 d−1), and 0.450 d−1 (0.378 to 0.522 d−1) for the 3 groups, respectively. Such heterogeneity in virus dynamics could be a confounding variable if it is associated with treatment allocation in compassionate use programs (i.e., observational studies).Subsequently, we mimicked randomized controlled trials of antivirals by simulation. An antiviral effect causing a 95% to 99% reduction in viral replication was added to the model. To be realistic, we assumed that randomization and treatment are initiated with some time lag after symptom onset. Using the duration of virus shedding as an outcome, the sample size to detect a statistically significant mean difference between the treatment and placebo groups (1:1 allocation) was 13,603 and 11,670 (when the antiviral effect was 95% and 99%, respectively) per group if all patients are enrolled regardless of timing of randomization. The sample size was reduced to 584 and 458 (when the antiviral effect was 95% and 99%, respectively) if only patients who are treated within 1 day of symptom onset are enrolled. We confirmed the sample size was similarly reduced when using cumulative viral load in log scale as an outcome.We used a conventional virus dynamics model, which may not fully reflect the detailed mechanisms of viral dynamics of SARS-CoV-2. The model needs to be calibrated in terms of both parameter settings and model structure, which would yield more reliable sample size calculation.ConclusionsIn this study, we found that estimated association in observational studies can be biased due to large heterogeneity in viral dynamics among infected individuals, and statistically significant effect in randomized controlled trials may be difficult to be detected due to small sample size. The sample size can be dramatically reduced by recruiting patients immediately after developing symptoms. We believe this is the first study investigated the study design of clinical trials for antiviral treatment using the viral dynamics model.

The design and machining of globoidal cam is difficult, because the shape of working surface is complex,and the curved surface of its space is undevelopable. Based on the above reasons,we proposed the parametric Modeling method for globoidal cam based. Through the secondary development, we realized the parameterized modeling of globoidal cam. Base on using of globular indexing cam NC milling machine existing in the lab,research the programming technology,analyses the defects of conventional programming method,raise improvement measures,control the programming error,modify the feeding speed,develop the special purpose programming software, creat globular indexing cam NC machining program automaticly ,improve the machining precision and efficiency of globular indexing cam. DOI: http://dx.doi.org/10.11591/telkomnika.v11i2.2027 Full Text: PDF