Optimal Pressure Profile Research Articles

#5555 TAKAYASU ARTERITIS IN THE TIME OF SARS-COV-2

Abstract Background and Aims SARS CoV 2 infection is characterized by pulmonary, cardiovascular, neurological and other complications. New onset hypertension after SARS Cov 2 infection was observed in various studies with an unclear mechanism. Vessel inflammation is a common finding in these patients. Case A young woman (24 years old) referred to our Unit for high blood pressure levels appeared few days after SARS COVID 2 infection. She had a positive familiar history of hypertension. A 24 hours blood pressure monitoring confirmed hypertension and the patient was treated with a beta-blocker and referred to the nephrologist. Physical examination was negative and peripheral pulses were palpable. Blood pressure was 150/90 mmHg without significative discrepancy (<10 mmHg) between right and left arm and between upper and lower limbs. Carotid-femoral and carotid-radial pulse wave velocity was in the upper limit of the normal range (9.8 and 8.0 m/sec respectively), renal function was preserved (serum creatinine 0.6 mg/dl, eGFR 154 ml/min) and proteinuria was 450 mg/die. C-reactive protein was 13 mg/L. Complement components C3 and C4 as well as IgG and anti-neutrophil cytoplasmic antibody (ANCA) levels were in the normal range. IgA and IgM were slightly elevated and anti-nuclear antibody (ANA) levels were 1:160. TSH was in the normal range. Patient was switched to calcium channel blockers and a screening to exclude secondary hypertension was performed. Hormonal profile showed hypersecretion of cortex and medullary adrenal gland (high renin and aldosterone, plasma and urinary cortisol, and epinephrine levels). Patient was treated with ACE inhibitor and showed an optimal blood pressure profile. Abdominal-Chest CT angiography detected no increase in adrenal gland dimension. Conversely, a left renal artery stenosis and a mild enlargement of the para-aortic tissue, suggestive of a retroperitoneal fibrosis, was described (Figure 1). A Doppler ultrasound examination confirmed a high systolic peak velocity in left renal artery and a low resistive index in the left kidney. According to the diagnosis of renal fibrosis, patient was treated with oral prednisone at a dosage of 1 mg/Kg/BW. Three months later, Doppler ultrasound and CT were materially unchanged. After a case revision and a negative evidence of inflammation at PET-FDG examination, the Takayasu Arteritis diagnosis was formulated and the patient underwent left renal artery angioplasty. Oral prednisone was tapered and methotrexate was started. One month later blood pressure and Doppler ultrasound velocimetric parameters were normalized. Conclusion This case report suggests that Takayasu arteritis may occur after SARS COVID 2 infection.

Numerical optimization of warm hydromechanical deep drawing process parameters and its experimental verification

Abstract Warm Hydromechanical Deep Drawing (WHDD) is considered as an effective sheet metal forming process to overcome low formability problems of lightweight materials, such as aluminum and magnesium alloys, at room temperature. WHDD process combines the advantages of Hydromechanical Deep Drawing (HDD) and Warm Deep Drawing (WDD) processes. In this study, interactive and combined effects of Pressure (P) and Blank Holder Force (BHF) variation on the formability of the AA 5754 aluminum alloy sheets in the WHDD process were investigated experimentally and numerically. Different from available studies, the optimal fluid pressure (P) and blank holder force (BHF) profiles, which were determined numerically using adaptive FEA integrated with fuzzy logic control algorithm (aFEA-FLCA), were validated experimentally for the first time in literature. Consequently, limiting drawing ratios (LDR) of AA5754 material were recorded as 2.5, 2.625, and 3.125 for HDD, WDD, and WHDD processes, respectively. Thus, it was demonstrated that the formability of lightweight materials, such as AA5754, could be increased significantly using the WHDD process through the proposed optimization method. This method was also implemented into the WHDD of an industrial part with complex geometry, successfully forming sharp features with minimal thinning at reduced levels of force, pressure, and time. Consequently, it is reasonably to state that the method developed in this study can be adopted for the manufacturing of any other part using the WHDD process.

Multi-objective optimization for minimizing weldline and cycle time using variable injection velocity and variable pressure profile in plastic injection molding

Since weldline in plastic injection molding (PIM) has an influence on not only the strength but also the surface appearance of a plastic product, it is preferable to reduce it as much as possible for high product quality. High mold temperature will be valid to the weldline reduction, but long cycle time is required for cooling down the plastic product. Generally, short cycle time is required for high productivity and the cycle time should be minimized. The trade-off between product quality and productivity is always observed in the PIM. In this paper, the weldline reduction and the cycle time are considered for the product quality and the productivity. In particular, the variable injection velocity and the variable pressure profile are adopted for simultaneously improving them. Numerical simulation in the PIM is so intensive that a sequential approximate optimization (SAO) using a radial basis function (RBF) network is adopted to determine the optimal injection velocity and pressure profile with a small number of simulations. The trade-off between the weldline and the cycle time is clarified through the numerical result, and the experiment (GL100, Sodick) is carried out to confirm the validity of the proposed approach.

Application of a new integrated optimization approach in sheet hydroforming process

The purpose of this study is to produce a desired hydroformed product under the optimal pressure profile. To achieve this purpose, a new adaptive optimization approach is proposed based on fuzzy logic control (FLC) integrated with simulated annealing (SA) optimization technique and ANSYS parametric design language (APDL). An intermediate MATLAB code was developed and used to manage data transfer automatically between FLC, SA and APDL, in which there would be no need for any interaction of user/designer during the optimization process execution. This method aims to find the optimal pressure loading profile, prevent wrinkling and necking failures, reduce unsuccessful iterations, and enhance convergence precision. This method is capable of adaptively changing the process parameters in order to reach the optimized values with higher accuracy in a more reasonable time. The results show a good agreement between the proposed optimization approach and experiments. The developed optimization approach is a practical and reliable design tool for industrial production of any symmetric shell cups using hydroforming process.

Ideal cardiovascular health and the subclinical impairments of cardiovascular diseases: a cross-sectional study in central south China

BackgroundIdeal cardiovascular health (CVH) is related to a low cardiovascular disease risk profile. This study aimed to investigate CVH metrics with both the biomarkers and markers of subclinical impairments of cardiovascular diseases (CVDs) in subjects from central south China.MethodsThe ideal CVH score (non-smoking status; ideal body mass index; regular physical activity; healthy diet; and an optimal serum cholesterol, blood pressure, and glucose profile; 1 point for each; total score: 0–7) was collected from 3009 participants without a history of CVDs. Subclinical biomarkers were assessed using C-reactive protein, homocysteine, and microalbuminuria. The presence of subclinical disease markers was defined as having at least one of the following: increased carotid intima-media thickness, carotid plaque, left ventricular hypertrophy, left ventricular systolic dysfunction, or a reduced ankle-brachial index. The association of biomarkers and markers with the CVH score was evaluated using multivariate logistic regression and linear regression analyses.ResultsOnly 0.2% of the study participants met all 7 ideal CVH metrics (CVH score = 7). Compared to the female participants, the male participants had poorer CVH profiles and a higher incidence of subclinical lesions (P < 0.05). In the fully adjusted models, per 1-unit increase in the CVH score was inversely associated with the biomarker levels (β = -0.092 – -0.224, P < 0.05 for all) and the odds of the presence of markers (odds ratio, 0.808; 95% confidence interval, 0.755–0.865). Similar relationships were observed in the gender subgroups and were stronger in the females.ConclusionA clear inverse association was observed between the biomarkers or markers of subclinical impairments and the CVH score in a central south Chinese population, implying the importance of ideal CVH for the primordial prevention of CVDs.

Mixed-integer programming models for line pressure optimization in shale gas gathering systems

In this work we propose a mixed-integer nonlinear programming model to address the line pressure optimization problem for shale gas gathering systems. This model is designed to determine: a) the optimal timing for turning prospective wells in-line, b) the optimal pressure profile within a gathering network, and c) the necessary compression power for delivering produced gas to long-distance transmission lines.We rely on a pressure-normalized decline curve model to quantify how line pressure variations impact the gas production of individual wells. The reservoir model itself is incorporated in a transmission optimization framework which rigorously evaluates pressure drops along pipeline segments. Moreover, we explicitly consider compression requirements to lift line pressure from gas gathering levels to setpoints dictated by transmission pipeline companies. Since the resulting optimization models are large-scale, nonlinear and nonconvex, we propose a solution procedure based on an efficient initialization strategy. Finally, we present a detailed case study, and show that the proposed optimization framework can be used effectively to manage line pressures in shale gas gathering systems by properly scheduling when, and how many, new wells are brought online.

An intelligent optimization–based prediction model for natural gas hydrate formation in a deepwater pipeline

ABSTRACTTemperature, pressure, and composition of gas mixtures in deepwater pipelines promote rapid formation of gas hydrates. To avert this dilemma, it is more significant to find out the temperature and pressure limits in gas hydrates formation of the deepwater pipeline. The objective of this research is to develop an optimization method that finds the optimal temperature and pressure profile for natural gas hydrate formation conditions and an error calculation method to find the realistic approach of the hydrate formation prediction model. A newly developed correlation model is computing the hydrate formation pressure and temperature for a single component of methane (CH4) gas. The proposed developed prediction model is based on the 2 and 15 constant coefficients and holds a wide range of temperature and pressure data about 2.64 to 46°C and 0.051 to 400 MPa for pure water and methane, respectively. The reducing error discrepancies are 1.2871, 0.35012, and 1.9052, which is assessed by GA, PSO, and GWO algorithms, respectively. The results show the newly developed optimization algorithms are in admirable compliance with the experimental data and standards of empirical models. These correlations are providing the capability to predict gas hydrate forming conditions for a wide range of hydrate formation data.

Combining the pressure effect with local heat treatment for improving the sheet metal forming process

The present work deals with the advantages in the Hydromechanical Deep Drawing (HDD) when AA5754 Tailored Heat Treated Blanks (THTBs) are adopted. It is well known that the creation of a suitable distribution of material properties increases the process performance. When non heat-treatable alloys are considered, the THTB approach can be successfully applied to increase the Limit Drawing Ratio (LDR) by changing the peripheral zone into the annealed state starting from a cold-worked blank. If this approach is combined with the advantages of a counterpressure, even more remarkable improvements can be achieved. Due to the large number of involved parameters, the optimized design of both the local treatment and the pressure profile were investigated coupling an axial symmetric Finite Element model with the integration platform modeFRONTIER. Results confirmed the possibility of increasing the LDR from 2.0 (Deep Drawing using a blank in the annealed state) up to about 3.0 if combining the adoption of a THTB with the optimal pressure profile.

An Approximate Optimal Maximum Range Guidance Scheme for Subsonic Unpowered Gliding Vehicles

This study investigates the maximum gliding range problems of subsonic unpowered gliding vehicles and proposes an approximate optimal maximum range guidance scheme. First, the gliding flight path angle corresponding to constant dynamic pressure is derived. A lift-to-drag ratio(L/D)inversely proportional to the dynamic pressure is then proven. On this basis, the calculation method of an optimal dynamic pressure (ODP) profile with a maximumL/Dthroughout the flight is presented. A guidance scheme for tracking the ODP profile, which uses the flight path angle as control variable, is then designed. The maximum ranges of the unpowered gliding vehicle obtained by the proposed guidance scheme and pseudospectral method are compared. Results show that the guidance scheme provides an accurate approximation of the optimal results, and the errors are less than 2%. The proposed guidance scheme is easy to implement and is not influenced by wind compared with numerical schemes.

An Assessment for Hydraulically Efficient Design of Uniformly Sloping Submain Lines

AbstractDetermining the actual pressure head profiles along the submain lines with a uniform slope is very important for proper hydraulic design of water distribution systems. In practice, there are three general pressure head profiles (Type I, Type II, and Type III) along submain lines depending on different uniform line slope situations. Of all types of pressure profiles, the Type IIb profile is considered the optimal (or ideal) pressure profile which can produce the minimum pressure head difference for a given pipe length. This profile occurs when the total energy loss by friction is just balanced by the total energy gain due to uniform downslope. This paper presents a comprehensive analysis based on the energy–gradient ratio (EGR) approach to identify the optimal (or ideal) pressure profile (Type IIb), to achieve the minimal point of the relative maximum pressure variation, ΦH, which can be defined as the ratio of the maximum allowable pressure head difference (∆Hmax) to the total friction drop (hf(L)). This minimal point is regarded as 'the most efficient pressure profile' or 'ideal hydraulic design' in the existing literature. For this purpose, an illustrative figure (Figure 4) was developed to compare values of the relative maximum pressure variation versus the dimensionless EGR (KS = S0/Sf) for all types of pressure profiles. In this figure, the present ϕH curve versus KS values allows the design engineer to make a decision for the best alternative for selecting the KS value, where for a given pipe slope (S0) the KS value can be selected to meet the minimum pressure variation [KS =1, (ϕH)min =0.36] or the range of pressure variation as close to the minimum point as possible. The present design technique may provide a useful decision support tool for achieving a good design solution among hydraulically possible alternatives with minimal pressure head difference, and results in a higher level of water application uniformity along the multi‐outlet pipeline system. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Automotive Transmission Clutch Fill Control Using a Customized Dynamic Programming Method

Clutch to clutch shift control technology, which is the key enabler for a compact and low cost transmission design, is important for both automatic and hybrid transmissions. To ensure a smooth clutch to clutch shift, precise synchronization between the on-coming and off-going clutches is critical. This further requires the on-coming clutch to be filled and ready for engagement at the predetermined time. Due to the compact design, currently there is no pressure sensor inside the clutch chamber, and therefore the clutch fill can only be controlled in an open loop fashion. The traditional clutch fill approach, by which the clutch fill input pressure command is manually calibrated, has a couple of limitations. First, the pressure profile is not optimized to reduce the peak flow demand during clutch fill. Moreover, it is not systematically designed to account for uncertainties in the system, such as variations of solenoid valve delay and parameters of the clutch assembly. In this paper, we present a systematic approach to evaluate the clutch fill dynamics and synthesize the optimal pressure profile. First, a clutch fill dynamic model, which captures the key dynamics in the clutch fill process, is constructed and analyzed. Second, the applicability of the conventional numerical dynamic programming (DP) method to the clutch fill control problem, which has a stiff dynamic model, is explored and shown to be ineffective. Thus, we proposed a customized DP method to obtain the optimal and robust pressure profile subject to specified constraints. The customized DP method not only reduces the computational burden significantly, but also improves the accuracy of the result by eliminating the interpolation errors. To validate the proposed method, a transmission clutch fixture has been designed and built in the laboratory. Both simulation and experimental results demonstrate that the proposed customized DP approach is effective, efficient and robust for solving the clutch fill optimal control problem.

FEA-Based Optimization of Blank Holder Force and Pressure for Hydromechanical Deep Drawing of Parabolic Cup using Greedy Search and RSM Methods

The greedy search and response surface methods are presented to determine the optimal process parameters of the linear pressure and constant blank holder force profiles for hydromechanical deep drawing of a parabolic cup using the finite element analysis. The optimization goal is to obtain the process parameters that minimize part thinning without any defect of the cracks and wrinkles. Part thinning and geometry-based wrinkle constraint functions are employed to quantify the cracking and wrinkling severity. A response surface of the part minimum thickness as a function of the maximum internal pressure and blank holder force is constructed by using the data collected during the greedy search. The optimum process parameters are then determined from the obtained surface. It is found that the method is capable to determine the optimal blank holder force and linear pressure profiles for the hydromechanical deep drawing of the parabolic cup.

Effects of granule size and distribution on the cold isostatic pressed alumina

Green alumina parts large in dimension are usually fabricated by cold isostatic pressing (CIP), whose properties, including green strength, green density gradient, and compression ratio, are usually affected by the mean size and size distribution of the spray-dried alumina granules. Such effects on the green parts subsequently dictate the sintered structure of alumina, microscopically and macroscopically, if the pressing profile during pressing is not optimized. In this study, alumina granules were spray-dried using an emulsified acrylic polymer as the binder. Granules of various sizes and size distributions were sieved, including sizes ranging between 200 mesh and 180 mesh, ranging between 180 mesh and 120 mesh, ranging between 120 mesh and 80 mesh, ranging between 80 mesh and 40 mesh, larger than 40 mesh and nature granules form without sieved. These six kinds of granules along with the as-spray-dried granules were then cold-isostatic-pressed into green parts. The pressure profile during pressing was varied, in order to optimize the properties of the green parts and the sintered parts. The granules were examined using scanning electron microscope while the green parts were analyzed by green density measurement. The green parts were subsequently sintered at 1600 °C, and density measurement, and scanning electron microscopic examination were carried out to compare the differences caused by the variation in granule size distribution. The results indicated that small granules experienced a very large pressing shrinkage ratio, which could cause severe shape distortion in under-cut region. The drawbacks of green parts arising from the granule size distribution could be compensated by optimal pressure profile design. With such a compensated action during cold isostatic pressing, uniform sintered structures could be attained.

Plasma profile and shape optimization for the advanced tokamak power plant, ARIES-AT

An advanced tokamak plasma configuration is developed based on equilibrium, ideal MHD stability, bootstrap current analysis, vertical stability and control, and poloidal field coil analysis. The plasma boundaries used in the analysis are forced to coincide with the 99% flux surface from the free-boundary equilibrium. Using an accurate bootstrap current model and external current drive profiles from ray tracing calculations in combination with optimized pressure profiles, β N values above 7.0 have been obtained. The minimum current drive requirement is found to lie at a lower β N of 6.0. The external kink mode is stabilized by a tungsten shell located at 0.33 times the minor radius and a feedback system. Plasma shape optimization has led to an elongation of 2.2 and triangularity of 0.9 at the separatrix. Vertical stability could be achieved by a combination of tungsten shells located at 0.33 times the minor radius and feedback control coils located behind the shield. The poloidal field coils were optimized in location and current, providing a maximum coil current of 8.6 MA. These developments have led to a simultaneous reduction in the power plant major radius and toroidal field from those found in a previous study [S.C. Jardin, C.E. Kessel, C.G. Bathke, D.A. Ehst, T.K. Mau, F. Najmabadi, T.W. Petrie, the ARIES Team, Physics basis for a reversed shear tokamak power plant, Fusion Eng. Design 38 (1997) 27].

Design Sensitivity Analysis Applied to Injection Molding for Optimization of Gate Location and Injection Pressure

Abstract In this work, we develop a numerical simulation method to optimize the injection molding process using the design sensitivity analysis (DSA). The optimization concerns the filling stage and focuses on the location of gates in the mold cavity as well as the injection pressure profile, in order to minimize the fill time. Since the problem to be solved involves transient flow with free surface (flow front), the direct differentiation method is used to evaluate the sensitivities of the Hele-Shaw, filling fraction and energy equations with respect to the design variables used in the analysis. The search domain parameterization is coped with using B-spline functions. Sensitivity and state equations are solved by means of finite element method. The proposed numerical approach is combined with the sequential linear and quadratic programming method of the design optimization tools (DOT) to find new design variables at the end of each complete filling simulation. Starting from any initial gate locations and injection pressure profile, the iterative optimization procedure enables us to find the optimal gate locations together with the optimal injection pressure profile. Finally, numerical results involving complex mold geometries are presented and discussed to assess the validity and robustness of the proposed method.

Plasma magnetic insulation

Theoretically the strong magnetic field of a tokamak should confine electrons and ions in a high-temperature plasma sufficiently well. However, the behaviour of electrons turns out to be anomalous, especially with application of auxiliary heating. This behaviour is discussed in the framework of dimensional analysis and a hypothesis of plasma transition into a relaxed state with a minimal energy subjected to the single constraint, namely conservation of the total current. Plasma tends to relax to the optimal current-density and pressure profiles, any deviation from which results in a additional heat transfer via the micronoise pumping by the magnetic island structure. This effect is more pronounced with an increase of n / I p , where n is the density, I p is the plasma current.

Self-organization in a tokamak plasma

The observed tendency for certain optimal current-density and pressure profiles to be maintained can be interpreted if one assumes a relaxed state in the plasma, which corresponds to minimal total energy for a given current. With optimal power deposition, when the current-density and pressure profiles also remain optimal, ohmic scaling may be maintained up to fairly high densities, i.e., fairly high βp. If the power deposition profile deviates from optimal, the plasma resists deviation from the optimal profiles, and the more so the higher βp. The thermal-conductivity profile is modified to maintain the relaxed state. Nonoptimal profiles may lead to degradation in the global energy lifetime τE, which can be related phenomenologically to pumping of magnetic noise by the excess free energy δF. Our argument provides a qualitative explanation of the self-organization physics.