Optimization Criteria Research Articles

Numerical energy and entropy analyses of a tube with wavy tape insert including CoFe2O4/water nanofluid under laminar regime

The primary objective of this investigation is to assess the impact of vortex generator geometry and nanofluid on thermohydraulic and irreversibility characteristics within a laminar flow regime. The study introduces an original CoFe2O4/H2O (1 % vol.) nanofluid and employs a wave tape insert to induce forced convection in a tube, accompanied by first and second-law thermodynamic analysis. The novelty of this research lies in the numerical exploration of heat transfer and flow profiles for a nanofluid in a tube, varying the wave rate (y = 4-5-6). The investigation considers the laminar model and single-phase approach in all analyses under constant heat flux (q” = 2000 W/m2). The study observed that the nanofluid flowing in the tube with a wave ratio of 4, 5, and 6 resulted in an average enhancement in the Nusselt number of 93.25 %, 86.26 %, and 80.06 %, respectively. The optimal performance evaluation criterion (PEC) for water flowing in the tube with a wave ratio of 6 at Re = 500 exhibited an increase of 11.0 %, whereas the CoFe2O4/H2O flow showed a 9.14 % increment in the average PEC along the Reynolds number. Moreover, the total entropy generation values for water flowing in tubes with wave ratios of 5, 6, and 4 exhibited increases of 101.88 %, 94.66 %, and 51.34 %, respectively, in comparison to the smooth tube.

Optimization of cross-sectional dimensions of castellated beams with hexagonal openings

The object of this study is a castellated beam, in which the web openings have the shape of a regular hexagon. The beam is examined to find optimal cross-sectional dimensions. The optimization task is stated as the task of finding the optimal profile numbers for top and bottom Tees of the beam and the optimal width of the web opening while ensuring the required load-carrying capacity of the beam. Minimization of the volume of the beam material was considered as an optimality criterion. The stated optimization problem was solved using the exhaustive search method. For an assortment of normal I-beams with parallel flanges, castellated beams were obtained with optimal cross-sectional dimensions depending on the steel grade, the beam span, and the magnitude of transverse uniformly distributed load. The optimization calculations proved that it was possible to increase the elastic section modulus of the beam to 35.48...50 % through the use of a castellated web. Castellated beams with optimal cross-sectional dimensions at the same load-carrying capacity are characterized by lower steel consumption (up to 23.19 %) compared to I-beams with a solid web. Analysis of the results has made it possible to devise recommendations for the optimal distribution of material in the cross-sections of such beams. The results are valid only for the assortment of normal I-beam profiles and only for the case of uniformly distributed load acting on the beam when the compressed beam flange is laterally restrained from the bending plane and the beam web has openings in the form of regular hexagons. It is under such conditions that the reported results can be implemented in practice both at the stage of selecting cross-sections of the studied class of structures, and at the development of effective assortments of castellated beams

NON-ANALYTICAL DESIGN OF THE PI CONTROLLER OPTIMAL PARAMETERS FOR A CONTINUOUS LINE

The multiple motor drives are complex and coupled MIMO nonlinear systems. Due to the complexity of their mathematical models the development of effective control systems is quite complicated task. This paper presents the design of optimal control based on the quadratic optimality criterion for the central section of the continuous production line using soft computer methods when fuzzy model of the controlled system has been used. In this case, the proposed method demonstrates non-analytical design of the optimal parameters of PI controller with emphasis on minimal knowledge on the controlled system. The realized experimental measurements on a continuous line laboratory model confirmed the effectiveness and the good dynamic properties of the optimal continuous line controller and also its applicability to others MIMO nonlinear dynamic systems.

Optimization of rotor blind hole parameters for inner-hole rotary cavitator

Abstract In order to study the cavitation characteristics of rotary cavitator and the optimization of blind hole parameters, this paper first deduces the blind hole geometric parameters (aperture, hole depth, and number of holes) that affect the cavitation effect, then uses a numerical simulation method to optimize the blind hole parameters that affect the cavitation effect based on the control variable method and gas phase contour. Using single factor analysis as the optimization criterion and gas phase volume as the optimization basis, the response surface method was applied to the multi-parameter optimization problem with interaction. The results indicate that the intensity of cavitation can be effectively increased by increasing the geometric dimensions of the blind holes’ diameter, depth, and number appropriately. On the other hand, the response surface method can be utilised to study the multi-parameter optimization problem in the multivariable system comprised of the geometric parameters of the blind hole of the cavitator rotor. This paper’s optimization research on the rotor parameters of inner-hole rotary cavitator provides a foundation and reference for future cavitator structure optimization research.

Data-driven strategies for enhancing diversity in oncology clinical trials: Optimization of eligibility criteria.

11020 Background: Advancing inclusive clinical research is essential to benefit all patients (pts) and is an expectation, and in some cases a requirement, by regulators. Enabling the inclusion of representative populations should begin at protocol design. However, it is not always clear which changes in eligibility criteria (EC) will have the most impact on representativeness and whether the impact will have similar effect across historically underrepresented populations (HUPs; i.e., pts ≥75 yrs, females, non-Latinx[NL] Black, or Latinx pts). We have defined a novel application of scoring to assess implications of EC on inclusion of HUPs in trials. Methods: Using real-world data from the US nationwide Flatiron Health electronic health record-derived de-identified database for aNSCLC as a benchmark (N=50,263), we selected pts who met trial EC and therapy indication criteria for 9 Phase III aNSCLC trials (2012–2018). We quantified representativeness of the eligible cohort via log disparity [LD], a machine learning fairness metric for the odds of selecting a subgroup vs. the rest of the population; 100% represents parity and 80% is sometimes considered a lower bound for representativeness, but higher benchmarks (e.g., 95%) may be more appropriate. We then identified EC drivers of representativeness by removing or modifying EC. Results: Across HUP groups, the majority of trials (≥55%) were below parity. Removing creatinine clearance (CrCl) had a consistently positive impact for older pts (median % Δ [range]: +2 [1, 32]) and NL Black pts (+2 [1, 5]), but the direction of impact differed across trials for female and Latinx pts (increase in representativeness for some trials, decrease for others). The impact of removing ECOG Performance Status (PS) varied across HUPs (positive for older pts, neutral or positive for female pts, trial-dependent for Latinx and NL Black pts); e.g., in Keynote010, removing ECOG PS increased LD for older pts (93% to 99%), but decreased LD for Latinx pts (97% to 93%). Across trials, removing hemoglobin, HIV, and Hepatitis B/C had a consistently positive or neutral impact on LD for NH Black pts (e.g., hemoglobin median % Δ [range]: +3 [2, 5]), however, the impact was negative or trial-dependent for Latinx and older pts. LD scores can also guide modification of cutpoints to optimize representativeness; e.g., for Keynote189, lowering the CrCL cutpoint from 50 to to 37 mL/min could be expected to improve representativeness for older patients (LD: 66% to 80%, the lower bound for representativeness). Conclusions: It is important to consider the complex nature of diversity when designing trials to ensure that optimizing inclusion of one group of pts does not inadvertently reduce representativeness for another group. These findings support a data-driven approach to modifying EC during protocol design to maximize inclusion of HUPs in concert with a robust operational plan.

Evidence-based clinical recommendations for hypofractionated radiotherapy: exploring efficacy and safety - Part 2. Lung (non-small cell lung cancer).

Several recent studies have investigated the use of hypofractionated radiotherapy (HFRT) for various cancers. However, HFRT for non-small cell lung cancer (NSCLC) with or without concurrent chemotherapy is not yet widely used because of concerns about serious side effects and the lack of evidence for improved treatment results. Investigations of HFRT with concurrent chemotherapy in NSCLC have usually been performed in single-arm studies and with a small number of patients, so there are not yet sufficient data. Therefore, the Korean Society for Radiation Oncology Practice Guidelines Committee planned this review article to summarize the evidence on HFRT so far and provide it to radiation oncology clinicians. In summary, HFRT has demonstrated promising results, and the reviewed data support its feasibility and comparable efficacy for the treatment of locally advanced NSCLC. The incidence and severity of esophageal toxicity have been identified as major concerns, particularly when treating large fraction sizes. Strategies, such as esophagus-sparing techniques, image guidance, and dose constraints, may help mitigate this problem and improve treatment tolerability. Continued research and clinical trials are essential to refine treatment strategies, identify optimal patient selection criteria, and enhance therapeutic outcomes.

Timing of immunotherapeutic strategies for first-episode Isolated Anti-Myelin Oligodendrocyte Glycoprotein-IgG Associated Optic Neuritis: A single-centre retrospective study

BackgroundThere is no consensus on the timing of immunotherapeutic strategies for the first-episode anti-myelin oligodendrocyte glycoprotein-IgG (MOG-IgG) associated disorders (MOGAD) presenting with isolated optic neuritis (ON). ObjectiveTo investigate the optimal timing of intravenous methylprednisolone therapy (IVMP) and necessity of immunosuppressive therapy for the first-episode isolated MOG-IgG associated ON (iMOG-ON). MethodsAdult patients with the first-episode iMOG-ON were enrolled. Primary outcomes were best-corrected visual acuity (BCVA) at last follow-up (i.e. final BCVA) and relapse, and their predictors were assessed by multivariate analysis. Results62 patients were included. Logistic regression analysis revealed BCVA at the time of IVMP (odds ratio: 0.463 (95 % confidence interval (CI) 0.310-0.714) was a factor predictive of regaining a final BCVA of 0.0 logMAR vision, and its Youden optimal criterion was <0.175 logMAR by plotting the receiver operating characteristic curve. The time-dependent cox proportional hazards model exhibited MMF therapy was not associated with a high likelihood of relapse-free survival (HR = 1.099, 95 % CI 0.892–1.354, P = 0.376) after adjusting for age of onset, gender, and baseline MOG serum titers. Similar analysis exhibited evidently negative association between high MOG-IgG serum titers at baseline and relapse-free survival after adjusting for age of onset, gender, and MMF therapy (HR = 0.339, 95 % CI 0.155–0.741, P = 0.007). ConclusionsDuring the first episode of iMOG-ON, the optimal timing of IVMP may be a short timeframe before visual acuity decreasing to 0.175 logMAR, and MMF therapy may not be recommended for patients with low MOG-IgG serum titers. Further long-term follow-up studies are required to validate these findings.

Definition of Virological Endpoints Improving the Design of Human Immunodeficiency Virus (HIV) Cure Strategies Using Analytical Antiretroviral Treatment Interruption.

Analytical treatment interruption (ATI) is the gold standard in HIV research for assessing the capability of new therapeutic strategies to control viremia without antiretroviral treatment (ART). The viral setpoint is commonly used as endpoint to evaluate their efficacy. However, in line with recommendations from a consensus meeting, to minimize the risk of increased viremia without ART, trials often implement short ATI phases and stringent virological ART restart criteria. This approach can limit the accurate observation of the setpoint. We analyzed viral dynamics in 235 people with HIV from 3 trials, examining virological criteria during ATI phases. Time-related (eg time to rebound, peak, and setpoint) and viral load magnitude-related criteria (peak, setpoint, and time-averaged AUC [nAUC]) were described. Spearman correlations were analyzed to identify (1) surrogate endpoints for setpoint and (2) optimal virological ART restart criteria mitigating the risks of ART interruption and the evaluation of viral control. Comparison of virological criteria between trials showed strong dependencies on ATI design. Similar correlations were found across trials, with nAUC the most strongly correlated with the setpoint, with correlations >0.70. A threshold >100 000 copies/mL for 2 consecutive measures is requested as a virological ART restart criterion. Our results are in line with recommendations and emphasize the benefits of an ATI phase >12 weeks, with regular monitoring, and a virological ART restart criterion of 10 000 copies/mL to limit the risk for patients while capturing enough information to keep nAUC as an optimal proxy to the setpoint.

Constrained Markov Decision Processes with Non-constant Discount Factor

This paper studies constrained Markov decision processes under the total expected discounted cost optimality criterion, with a state-action dependent discount factor that may take any value between zero and one. Both the state and the action space are assumed to be Borel spaces. By using the linear programming approach, consisting in stating the control problem as a linear problem on a set of occupation measures, we show the existence of an optimal stationary Markov policy. Our results are based on the study of both weak-strong topologies in the space of occupation measures and Young measures in the space of Markov policies.

Stepless Transmission Optimization for Green Micromobility

Small, electrified vehicles are becoming possible for urban environmental mobility due to their environmental performance, including zero-emission driving. Vehicles of this type use electric motors as sources of mechanical energy. Today, two types of transmission are most used in electrical micromobility vehicles (skateboards, scooters, tricycles, quadricycles, mopeds, motorcycles, go-karts, etc.): chain transmission and belt transmission. This transmission types provides a constant gear ratio that can only compromise between the maximum speed and the starting torque values, thus reducing the usage efficiency of the engine. This reduces vehicle manufacturers’ choice of less powerful drive and control elements, as well as balancing performance and efficiency at low and high speeds as well as on terrain.A novel design of a continuously variable transmission (CVT) for an electric go-kart is presented in this paper. The CVT consists of an inertial driving pulley mounted on an electric motor shaft, a timing V-belt, a gear wheel on the drive axle and 2 pressure rolls, which are moved by a servo motor for tensioning the V-belt. Gear ratio of a transmission can change seamlessly in the range of 1.5 - 2.2. The CVT has been tested under real conditions. The top speed of the electric go-kart with the given CVT and motor power 24.7 kW is 133km/h; time to accelerate to the top speed is 25 s. Total efficiency of the transmission (motor shaft, CVT, drive axle and wheels) is 65-72 % now, but there exist a lot of possibilities to improve it in the future. The conditions under which the novel CVT has an advantage over belt and chain transmissions with constant gear ratios have been studied. The developed mathematical model, the method for determination its constants, the algorithm for numerical calculations and the optimization criterion makes it possible to determine the optimal gear ratio for a vehicle with various CVT (not only belt) at any point in time in different racing modes. The model has been proved experimentally during acceleration and deceleration tests of the go-kart; it describes precisely the motion of the go-kart within the speed measurement error.The developed solution is applicable in urban micromobility. An optimized and stable transmission system focused on energy efficiency, resource saving, using less powerful drive and zero-emission.

Proposal of Set of Optimization Criteria and Their Specific Calculation for Effective Inventory Management in an Industrial Enterprise

Currently, there are many mathematical models and tools for inventory management and optimization. Based on the literature review, the authors conclude that inventory management tools and models are mostly one-sided and focused on the cost aspect of the inventory management process. The research goal was to propose a set of criteria for inventory optimization as a basis for the development of an inventory management model whose structure would consider both the economic aspect and the stochasticity of demand and the reliability of delivery. Optimization criteria are based on extensive analyses of influences and correlations between logistic chain subsystems in relation to inventory. The interactions of the subsystems are then mathematically expressed, which represents the main output of the created set of optimization criteria. The defined criteria can be used as a basis for creating a new optimization model of inventory management.

Equivalent Thermal Conductivity of Topology-Optimized Composite Structure for Three Typical Conductive Heat Transfer Models

Composite materials and structural optimization are important research topics in heat transfer enhancement. The current evaluation parameter for the conductive heat transfer capability of composites is effective thermal conductivity (ETC); however, this parameter has not been studied or analyzed for its applicability to different heat transfer models and composite structures. In addition, the optimized composite structures of a specific object will vary when different optimization methods and criteria are employed. Therefore, it is necessary to investigate a suitable method and parameter for evaluating the heat transfer capability of optimized composites under different heat transfer models. Therefore, this study analyzes and summarizes three typical conductive heat transfer models: surface-to-surface (S-to-S), volume-to-surface (V-to-S), and volume-to-volume (V-to-V) models. The equivalent thermal conductivity (keq) is proposed to evaluate the conductive heat transfer capability of topology-optimized composite structures under the three models. A validated simulation method is used to obtain the key parameters for calculating keq. The influences of the interfacial thermal resistance and size effect on keq are considered. The results show that the composite structure optimized for the V-to-S and V-to-V models has a keq value of only 79.4 W m−1 K−1 under the S-to-S model. However, the keq values are 233.4 W m−1 K−1 and 240.3 W m−1 K−1 under the V-to-S and V-to-V models, respectively, which are approximately 41% greater than those of the in-parallel structure. It can be demonstrated that keq is more suitable than the ETC for evaluating the V-to-S and V-to-V heat transfer capabilities of composite structures. The proposed keq can serve as a characteristic parameter that is beneficial for heat transfer analysis and composite structural optimization.

Ultra-high density mapping and ablation of localized microreentrant tachycardias: insight from the CHARISMA registry

Abstract Background The optimal criteria for distinguishing microreentrant atrial tachycardias (mAT) from macroreentrant atrial arrhythmias (MAT) in clinical practice have not been definitively established. Recent advancements in ultra-high-density mapping featuring automated functionalities, has enhanced our understanding of mAT circuits and the precise localization of foci. Purpose Our intent was to observe the diagnostic support provided by high density mapping and Lumipoint algorithm in mAT as well as the ablation outcomes. Methods Consecutive patients eligible for atrial tachycardia (AT) ablation in 22 Italian centres were prospectively enrolled. all ATs were comprehensively mapped in either the left or right atrium utilizing the Rhythmia mapping system and the 64-pole Orion basket catheter. A mAT was defined as an AT characterized by slow, continuous, low fragmented potentials covering a minimum of 50% of the tachycardia cycle length (CL) within a confined area (defined as a circuit within &amp;lt; 1 cm2), enclosed by a couple of closed splines of the Orion catheter, and exhibiting a centrifugal activation pattern to the rest of the atria. The Lumipoint tool was systematically employed to confirm electrogram fragmentation within this defined area. Results Among 159 ATs analysed, 97 (61.0%) were identified as MAT, 50 (31.4%) as focal atrial tachycardias and 12 (7.5%) as mAT. Of these latter, 6 patients (50%) had a previous history of atrial ablation procedure. Concerning the mAT group, the predominant origin site was the left atrium (10 mAT, 83,3%); the targeted activity was localized in the anterior wall in 4 cases (33.3%), in proximity to PVs in 3 cases (25%), along the left ridge in 2 cases (16.6%) and at the roof in 1 case (8,3%). In the remaining right mAT, the foci were found in the free wall and along the CTI in 1 case (8.3% each). The electrical activity spanning the whole CL was detected by 2.7±1.8 pairs of close bipoles of the Orion catheter, was confined to a region of 0.36±0.3cm2 with the longest component of fractionated EGM per spline equal to 64.7±17% of the CL. Low voltage areas (&amp;lt;0.1 mV) were detected in all mAT cases and colocalized with the origin site. Voltage level was 0.2±0.1mV at the site of longest duration of the fragmented potential. A single shot RF delivery terminated each arrhythmia at targeted location. Consolidative RF ablations were then delivered in the adjacent area. Over a median of 288 [248-349] days of follow-up, 5 (3.1%) patients suffered from an AT/AF arrhythmia recurrence and of these, 3 (3.1%) were in the MAT group, 1 (2%) in the focal AT and 1 (8.3%) in the mAT group. No complications were observed. Conclusions A novel automated algorithm for microreentrant atrial tachycardia identification, coupled with the identification of matched areas of electrogram fractionation by the Orion catheter, may restrict the extent of required ablation and result in a low arrhythmia recurrence.

Synchronous deautoconvolution algorithm for discrete-time positive signals via [formula omitted]-divergence approximation

We pose the problem of the optimal approximation of a given nonnegative signal yt with the scalar autoconvolution (x∗x)t of a nonnegative signal xt, where xt and yt are signals of equal length. The I-divergence has been adopted as optimality criterion, being well suited to incorporate nonnegativity constraints. To find a minimizer we derive an iterative descent algorithm of the alternating minimization type. The algorithm is based on the lifting of the original problem to a larger space, a relaxation technique developed by Csiszár and Tusnády in [Statistics & Decisions (S1) (1984), 205–237] which, in the present context, requires the solution of a hard partial minimization problem. We study the asymptotic behavior of the algorithm exploiting the optimality properties of the partial minimization problems and prove, among other results, that its limit points are Kuhn–Tucker points of the original minimization problem. Numerical experiments illustrate the results.

Redefinition of failure envelope of composite materials considering uncertainty of test data

After conducting three World-Wide Failure Exercises (WWFEs), it has become apparent that existing strength theories or criteria have certain deficiencies, and no single theory can accurately match all experimental results. As a result, there is a growing focus on the uncertainties present in the macrocosm test data of composite materials. The paper introduces the concept of uncertainty into the collection of test data for the classical Tsai-Wu failure criterion and Hashin criterion. The method proposed involves fitting the coefficients of the failure criteria by treating experimental data as random variables, a technique that diverges significantly from the conventional method of using composite allowable values to define these coefficients. It also uses the probability of success as a constraint and defines the fitted error as an optimization objective. Monte Carlo sampling is employed to perform a reliability analysis, and six sigma is used for a reliability-based optimization of the failure criteria. The Multi-Island Genetic Algorithm is utilized to search for the optimal value. The approach presented in this study provides the ability to predict future failures in composite materials by considering the uncertainty of the test data. By incorporating uncertainties into the analysis and design process, a more accurate and reliable assessment of the performance of composite materials can be achieved. Moreover, there seems to be a significant difference in the fitting error between the mean data and the normal distribution data. Additionally, when Hashin criterion is modified, the test data matches the failure envelope more closely and the degree of fit between the experimental data and the failure envelope is higher.

#2603 Focus on a crucial moment in decision making: evaluate peritoneal dialysis as incident renal replacement therapy

Abstract Background and Aims Chronic kidney disease affects 10% of the world population (15.1% in Spain, ENRICA 2019 study), being a health problem with important physical, emotional, and socio-occupational repercussions. Deciding on the most appropriate renal replacement therapy (RRT) for each patient, according to their lifestyle and family environment, represents a considerable challenge. Peritoneal dialysis (PD) offers several benefits, including greater independence, preserved kidney function, less restrictive diet, and better adaptation to the patient's lifestyle. It also improves the capacity for self-training and learning. Although kidney transplantation is the best RRT option, PD has demonstrated better quality of life, patient autonomy, and higher survival rates. Despite these advantages, PD as a technique for starting RRT represents 16.4% among incident patients in Spain, reaching 25% in our community, similar data to that of other northern European countries (ERA EDTA Report 2021). Method We carried out a retrospective descriptive study of patients followed in Advanced Chronic Kidney Disease (ACKD) over a period of five years (2017-2021). The inclusion criteria considered the acceptance of the technique in optimal candidates, with integrity of the peritoneal membrane and/or functional abdominal cavity, as well as the ability to learn the technique and family support. The study aimed to assess the percentage of patients who, meeting optimal criteria for PD candidacy, successfully initiated the technique. Results The analyzed population consisted of 113 patients, 73.4% males, with a mean age of 77 years. 59% of ACKD patients were considered candidates, and of these, 73% (n 38) chose PD as the modality, successfully initiating the technique. The main causes of abandonment or failure of the technique were: Out of the 38 patients successfully initiating PD as RRT, 34% continued with this modality. Conclusion PD provides quality of life and autonomy to patients who choose this technique. Individualized and ongoing training through updated information is essential during this process, as it helps reduce most complications and reinforces patient autonomy.

Classification with costly features in hierarchical deep sets

Classification with costly features (CwCF) is a classification problem that includes the cost of features in the optimization criteria. Individually for each sample, its features are sequentially acquired to maximize accuracy while minimizing the acquired features’ cost. However, existing approaches can only process data that can be expressed as vectors of fixed length. In real life, the data often possesses rich and complex structure, which can be more precisely described with formats such as XML or JSON. The data is hierarchical and often contains nested lists of objects. In this work, we extend an existing deep reinforcement learning-based algorithm with hierarchical deep sets and hierarchical softmax, so that it can directly process this data. The extended method has greater control over which features it can acquire and, in experiments with seven datasets, we show that this leads to superior performance. To showcase the real usage of the new method, we apply it to a real-life problem of classifying malicious web domains, using an online service.

Multi-objective optimization of heat treatment criteria on the corrosion and wear behaviour of ZA27/SiC/TiB2 hybrid metal matrix composite

The current study presents a methodology for examining the effect of solutionizing and aging parameters on the wear and corrosion behaviour of ZA27/SiC/TiB2, a Hybrid Metal Matrix Composite(HMMC). ZA27 alloy is widely used in applications where high bearing resistance and wear resistance properties are desired. However, its usability is limited to temperatures less than 1000 C as its properties exhibit a declining trend. The addition of SiC and TiB2 were found to contribute in circumventing this lacuna. Furthermore, no studies were reported on the process of augmenting the corrosion and wear resistance of this hybrid composite. This research gap is specifically addressed in this work. The chosen Hybrid Composite consisting of 15% of reinforcing elements(SiC + TiB2) proportioned equally among them along with 85% of ZA27 alloy matrix is produced by Mechanical Stir casting method. The experimental work has been broadly divided into two major spectrums. The first part consisting of analysing the change in properties being studied before and after heat treatment. Besides, this part of the work also involved the study of the variation in artificial aging temperature on the properties under consideration. The Potentiodynamic Polarisation tests showed that the solution heat treatment produces a significant decline in corrosion rate. Further, aging at a temperature of 1800 C has also evidently improved the properties of corrosion and wear resistance. However, results also depicted that over aging would deteriorate these properties. The final and subsequent part was completely devoted to identifying the best and optimised heat treatment parameters viz., solutionising time, aging temperature and time. Further, Taguchi L9 orthogonal array is taken to design the experiments in the second phase. Regression Equations were developed from the observations of this set of experiments. These equations were later subjected to Multi-Objective Genetic Algorithm (MOGA) which produces a pareto set of optimal solutions. The Pareto frontier was then analysed using Multi criteria decision making approaches viz., VIKOR, LINMAP and TOPSIS to arrive at the most optimal solution. This approach has culminated in an optimal solution of corrosion and Wear rates of 2.27mpy, 2.75 ˟ 10-3 mm3/m and coefficient of friction as 0.271 at the input variables of solutionizing time −5 h, aging temperature-1890 C and aging time-2 h.

Topology optimization of non-linear electromagnetic actuator based on Reluctance Network Analysis

Topology Optimization (TO) enables unrestricted exploration within a design domain and is typically based on a spatial discretization that is also used as the mesh for simulation. In this article, we propose to use for the simulation a mesh-based equivalent circuit method termed the Reluctance Network Analysis (RNA), with nonlinear magnetic properties of the material. The simulation tool is then used in a topology optimization process solved with generalized optimality criteria (GOC) method. During the optimization, the sensitivity matrix is needed, and we describe here how to derive the matrix in the case of a nonlinear RNA using Adjoint Variable Method (AVM). Finally, we implemented this topology optimization through a case study of an electromagnetic actuator.

The Best Time to Play the Lottery

The best time to play the lottery is when the jackpot has rolled over several times and grown large, but not so large that you must share the prize if you win. We examine maximizing the expected value of a winning ticket as well as that in a random ticket. The derived optimality criteria depend on the prize elasticity of ticket demand. A regression analysis on data obtained from the Mega Millions® and Powerball® multi-state lotteries suggests ticket sales grow quadratically in the size of the advertised lump-sum cash jackpot prize. With quadratic growth, the best time to play is when ticket sales are 1.25–2.5 times the jackpot odds, currently about 300 M to one for these two lotteries. Since ticket sales are not known to ticket buyers, we invert the regression function to prescribe the best time to play in terms of the cash prize. It turns out that these lotteries offer a (pretax) fair wager with positive expected value in a surprisingly wide interval of jackpot prizes. That is a good time to play; the best time is in the neighborhood of the nearly 1 $B record cash jackpot awarded in these lotteries in recent years.