Using optimal control to adjust the production rate of a deteriorating inventory system

AbstractThis work represents is another contribution to the application of optimal control theory to production inventory systems. We consider a firm that produces some product at a certain rate and aims at improving this rate. We successfully formulated the model as an optimal control problem and obtained an explicit solution using the maximum principle. An illustrative example is provided and the sensitivity of the model to some of the system parameters was addressed

A comparison of fracture strength among different brands of translucent zirconia crown restorations

Objectives: As the development of translucent zirconia crown using CAD/CAM technology, the usage of full zirconia crown is gradually increased. The purpose of this study was to investigate the highest fracture strength of translucent zirconia full zirconia crowns among different brands of translucent zirconia. Methods: Maxillary 1stpremolar resin teeth were prepared the total circumferential axial reduction was about (1 mm), and axial taper of 6°. Three brands of translucent zirconia (Whitepeaks, Imes-icor and Dentaldirect) that was used in three groups, every group contain five full zirconia crowns using CAD/CAM system (CAD/CAM system 250i, Imes-icor, Germany). The samples seated on the resin die using. All specimens were tested with a universal testing machine. Single load-to-fracture was applied on the lingual aspect of the facial cusp at a rate of 1mm/min. The specimens were thoroughly evaluated for bulk fracture with fractography. Results: Statistically high significant difference (p < 0.00) was found between the groups. The fracture strength of the groups varied Whitepeaks crowns was (2737.5 ± 106) N, which was significantly higher than the two overall mean fracture strength measured for the Imes-icor crowns (3620 ± 40) N and Dental direct crowns (3830 ± 130) N, the Dental direct highest fracture strength than other groups. Conclusions. The fracture strength of Dental direct crowns is considerably higher than that of Whitepeaks crown, The fracture strength of all the groups made of monolithic high translucent Y-TZP is exceeded human maximum bite force, sufficient for clinical use for the majority of patients.

GIS-based assessment of groundwater quality for drinking and irrigation purposes in central Iraq

In many parts of the world, groundwater is considered to be a key source of fresh water for both the domestic and non-domestic sectors. Where groundwater extraction is implemented, systems to monitor water quality must ensure a safe and sustainable supply. Over the years, Iraq has suffered from surface water quality and supply problems, necessitating groundwater extraction in many regions. This study investigates groundwater quality in a region of central Iraq around Babylon city, covering an area of 5119 km2. The data gathered for this study included maps, well locations and water quality data and was sourced from the relevant governmental departments. A base map of the focussed region was initially prepared following data collection. The analysed water quality parameters were used as an attribute database to produce thematic maps using a geographical information system (GIS) environment. In this paper, the water quality index (WQI) and the irrigation water quality index (IWQI) were calculated for different groundwater samples using various parameters including the Electrical Conductivity (EC), Cl−, HCO3−, Na+ and pH. Moreover, the groundwater suitability for irrigation purposes has been assessed using indices such as Kelly’s ratio (KR), sodium absorption ratio (SAR), residual sodium carbonate (RSC), soluble sodium percentage (SSP) and permeability index (PI). Water quality index maps have been developed using the GIS environment. The obtained results reveal that the groundwater in the study location requires specific treatments to be usable

Isolation and characterisation of microorganisms contaminating herbal infusion sold in Minna, Nigeria

The microbiological assessment of ten herbal infusion samples from ten different locations in Minna, Niger State was investigated. The assessment of the microbial contamination on the herbal products was carried out, using standard methods. Pour plate method was used to cultivate serially diluted portions of the medicinal plant infusion samples. The results revealed that all the herbal preparations had the presence of microbial contaminants. The total heterotrophic counts of the different herbal samples ranged from 0 cfu/mL to 25.0 × 108cfu/mL while the total fungal counts ranged from 3.0×106cfu/mL to 3.5×108cfu/mL. The total viable bacteria counts showed that the highest counts of 25.0 × 108cfu/mL was recorded in the sample from Bosso and the least counts of 0 cfu/mL from Kasuwan-Gwari while the total fungal counts showed that the highest count of 3.5×108cfu/mL was found in the sample obtained from FUT campus and the least counts of 3.0×106cfu/mL in the sample from Mai-Kunkele. One way analysis of variance (ANOVA) showed that there was significant difference (p<0.05) in the microbial load of the herbal infusions from each location. The microbial isolates identified were E. coli, Staphylococcus aureus, Shigella sp, Klebsiella sp, Pseudomonas sp, Micrococcus sp, Salmonella sp, Aspergillus sp, Penicillium sp and Saccharomyces cerevisaie. Members of the genus Aspergillus were found to be predominant. This suggests that the herbal infusion harbors microorganisms that could be hazardous to human health and hence producers should maintain the highest possible level of hygiene during the processing and packaging of the products in order to ensure safety of the products

Oil palm leaf fibre and its suitability for paper-based products

Due to the shortage of wood as origin materials for paper-based production, agro-residue materials have been explored in the quest of finding the best alternative fibre. Oil palm leaf (OPL) is one of agro-residue that has potential due to its comparable characteristics with wood fibre. Studies on chemical compositions, fibre morphology, and mechanical property of OPL have been carried out aiming to evaluate its potential as a substitute raw material for pulp and paper-based production. The chemical compositions were analysed according to the TAPPI standard, Kurscher-Hoffner and chlorite methods accordingly. The mechanical property (tensile, tearing and bursting strengths) were determined as described in TAPPI test methods. Fibre dimensions were determined using Franklin method and analysed under the optical microscope. The content of cellulose in the OPL is determined to be 43.8%. Although, this result is lower than wood fibre (53%), OPL has higher hemicellulose content (36.4%) than the wood fibre (27.5%). In addition, the lignin content (19.7%) of OPL is in the low range of those in wood resources (18 - 25%). These parameters are important components to produce good quality pulp and will provide high mechanical strength of the paper-based products. The measured fibre length of oil palm leaf (1.13 mm) is shorter than the wood fibre (1.90 mm). Meanwhile, the mechanical property of OPL showed lower indexes than wood resources, however, tear (1.80 mN.m2/g) and burst (0.95 kPa.m2/g) indexes of OPL are higher than other published and successful wood resources (Eucalyptus). Based on the analyses, the oil palm leaf is indeed a suitable alternative of raw material for pulp and paper-based industries

Picosecond excitation and selective intramolecular rates in supersonic molecular beams. IV. Alkylanthracenes

To assess the role of alkylation on IVR, the dynamics of jet cooled 9-methyl and 9-hexylanthracene excited to single vibronic levels (SVL) in S1 are investigated and compared with the parent molecule, anthracene, whose picosecond IVR dynamics are now well characterized. Vibrations in S1 and S0 are analyzed. Decay rates and SVL fluorescence spectra are also presented. The decay rates as a function of excess vibrational energy increase rapidly at low energy but become relatively constant at high energy. The approximate energy threshold at which the decay rate "saturates" is dependent on the substitutent; anthracene ([approximately-equal-to]1800 cm^−1), 9-methylanthracene ([approximately-equal-to]1000 cm^−1), 9-hexylanthracene ([approximately-equal-to]400 cm^−1), and A–(CH2)3–[cursive phi] (<=400 cm^−1). These identified thresholds are discussed and related to IVR processes. Finally, some comments on the importance of low frequency modes to IVR are given

Estimated Glycated albumin' levels early in pregnancy could detect women at risk to develop gestational diabetes mellitus

Background: Gestational diabetes mellitus (GDM) is characterized by dysfunction in maintaining glucose homeostasis leading to adverse maternofetal outcomes and this necessitates the use of markers for its early prediction. Objectives: To determine the ability of the estimated percentage of glycosylated hemoglobin (HbA1c%) and glycated albumin (GA%) at the 6th gestational week (GW) to define women liable to develop GDM. Patients and methods: 402 women were clinically evaluated and gave blood samples for estimation of fasting blood glucose (FBG) and HbA1c% and GA% at the 6th-8th GW. At the 24th GW, all women underwent the evaluation of insulin resistance (IR) using the Homeostasis model assessment of IR score and the 75-Oral Glucose Tolerance Test (75-OGTT) to diagnose GDM. The levels of estimated variate at the 6th-8th GW were statistically analyzed to define the predictor for GDM. Results: 62 women developed IR and 36 of them progressed to GDM. Statistical analyses defined FBG, GA%, HbA1c% as predictors for IR and GDM, but the Paired-sample area difference under the ROC curves defined high GA% as the significant positive predictor for GDM. Kaplan-Meier analysis defined GA% at 14% and 15% could define the risk for GDM by 20% and 40%, respectively but the evaluated performance characters at 15% were significantly (P=0.0074) higher than at 14 %. Conclusion: Estimation of GA% in blood samples obtained at the 6th-8th GW could predict the oncoming GDM with high specificity and negative predictive value at the cutoff of 15%

Effect of Milling Strategy on the Surface Quality of AISI P20 Mold Steel

This paper explores the impact of various milling strategies, including up-milling, down-milling, and hybrid approaches, on the surface roughness of AISI P20 mold steel. The study is methodically divided into three stages to comprehensively understand the effects of these strategies. The first stage involves milling single slots with varying cutting parameters to establish baseline effects. The second stage examines the effects of consistent milling strategies (up-up and down-down) on surface quality. The third stage probes into hybrid strategies (up-down and down-up) to assess their effectiveness. Central to this investigation is not only the type of milling strategy but also how cutting speed and feed rate influence the resultant surface roughness. Our findings indicate that up-milling generally leads to a 22% increase in surface roughness compared to down-milling. This trend is visually verified by surface texture analyses. When comparing consistent strategies, up-up milling tends to produce rougher surfaces than down-down milling by approximately 25%, characterized by distinctive scratches and feed mark overlays. Remarkably, while the hybrid milling strategies do not exhibit significant differences in surface roughness, variations in cutting speed and feed rate play a crucial role. Specifically, at lower speeds, hybrid milling achieves smoother surfaces than the identical double milling mode, while at a cutting speed of 100 m/min, the double mode demonstrates a notable decrease in roughness. Additionally, this study introduces a color mapping simulation for machined pockets, validated by experimental results, to predict surface roughness based on the strategic history of milling, thereby offering valuable insights for optimizing milling processes

A Closer Look at Precision Hard Turning of AISI4340: Multi-Objective Optimization for Simultaneous Low Surface Roughness and High Productivity

This article reports an extended investigation into the precision hard turning of AISI 4340 alloy steel when machined by two different types of inserts: wiper nose and conventional round nose. It provides a closer look at previously published work and aims at determining the optimal process parameters for simultaneously minimizing surface roughness and maximizing productivity. In the mathematical models developed by the authors, surface roughness at different cutting speeds, depths of cut and feed rates is treated as the objective function. Three robust multi-objective techniques, (1) multi-objective genetic algorithm (MOGA), (2) multi-objective Pareto search algorithm (MOPSA) and (3) multi-objective emperor penguin colony algorithm (MOEPCA), were used to determine the optimal turning parameters when either the wiper or the conventional insert is used, and the results were experimentally validated. To investigate the practicality of the optimization algorithms, two turning scenarios were used. These were the machining of the combustion chamber of a gun barrel, first with an average roughness (Ra) of 0.4 µm and then with 0.8 µm, under conditions of high productivity. In terms of the simultaneous achievement of both high surface quality and productivity in precision hard turning of AISI 4340 alloy steel, this work illustrates that MOPSA provides the best optimal solution for the wiper insert case, and MOEPCA results are the best for the conventional insert. Furthermore, the results extracted from Pareto front plots show that the wiper insert is capable of successfully meeting both the requirements of Ra values of 0.4 µm and 0.8 µm and high productivity. However, the conventional insert could not meet the 0.4 µm Ra requirement; the recorded global minimum was Ra = 0.454 µm, which reveals the superiority of the wiper compared to the conventional insert

Heavy fermions and two loop electroweak corrections to b→s+γb\rightarrow s+\gamma

Applying effective Lagrangian method and on-shell scheme, we analyze the electroweak corrections to the rare decay $b\rightarrow s+\gamma$ from some special two loop diagrams in which a closed heavy fermion loop is attached to the virtual charged gauge bosons or Higgs. At the decoupling limit where the virtual fermions in inner loop are much heavier than the electroweak scale, we verify the final results satisfying the decoupling theorem explicitly when the interactions among Higgs and heavy fermions do not contain the nondecoupling couplings. Adopting the universal assumptions on the relevant couplings and mass spectrum of new physics, we find that the relative corrections from those two loop diagrams to the SM theoretical prediction on the branching ratio of $B\rightarrow X_{_s}\gamma$ can reach 5% as the energy scale of new physics $\Lambda_{_{\rm NP}}=200$ GeV.Comment: 30 pages,4 figure