Optimal Level Research Articles

Response of Microbiological Properties to Short-term Nitrogen Addition in Perennial Alpine Cultivated Grassland

Removing nitrogen limitation is necessary to increase plant productivity in alpine grasslands. A short-term nitrogen addition experiment was conducted to understand the effects of nitrogen addition on the soil physicochemical properties and microbial community structure of perennial alpine cultivated grassland in the region around Qinghai Lake. From June to August 2022, four N application gradients （T0： 0 kg·hm-2·a-1, T1： 22.5 kg·hm-2·a-1, T2： 45 kg·hm-2·a-1, T3： 67.5 kg·hm-2·a-1） were set up in a four-age perennial cultivated grassland, and soil samples were collected from the 0-20 cm soil layer. The soil physical and chemical properties and microbial community structure were determined under the different treatments. The results showed that soil water content （SWC）, soil organic carbon （SOC）, ammonium nitrogen （NH4+-N）, nitrate nitrogen （NO3--N）, available nitrogen （AN）, available phosphorus （AP）, total phosphorus （TP）, total nitrogen （TN）, and total carbon （TC） tended to increase with the increase in nitrogen application level and the T3 treatment significantly decreased the soil pH. Nitrogen addition did not significantly alter the Alpha diversity of soil microbial communities and different levels of nitrogen application affected the structure of soil microbial communities to different degrees. The T1 and T2 treatments increased the number of soil bacteria and fungi and T3 treatment decreased the number of soil bacteria and fungi. Nitrogen addition increased the relative abundance of the dominant flora of Actinobacteriota, Zygomycota, Blastococcus, and Gibberella and decreased the relative abundance of the dominant flora of Proteobacteria, Bacteroidota, Sphingomonas, and Claroideoglomus. RDA analysis showed that SOC and soil electrical conductivity （EC） were the key soil physicochemical factors affecting changes in soil bacterial communities, and soil pH was the main factor affecting the distribution of soil fungal communities. Collectively, 67.5 kg·hm-2·a-1 may be the optimal level of N application to improve the soil environment of perennial alpine cultivated grasslands.

A randomized trial investigating the impact of response expectancy on the counting blessings intervention: the role of optimism as a moderator

IntroductionThis randomized controlled trial aimed to address a knowledge gap concerning the mechanisms responsible for the efficacy of gratitude interventions. Specifically, we investigated how various response expectancies (positive, ambiguous + negative, and no expectancy) impact the efficacy of the “counting blessings” intervention in influencing positive and negative emotions. Additionally, the study explores how optimism levels (high, medium, low) interact with these expectancies to influence intervention efficacy.MethodA total of 529 adult volunteers were recruited through social media and randomly assigned to one of three experimental conditions, Positive Condition (PC), Ambiguous + Negative Condition (ANC), No Expectancy Condition (NEC), using a Random Sequence Generator. Of these, 142 participants completed the seven-day counting blessings intervention, and 111 participated in a follow-up assessment 1 month later. Missing data were addressed using multiple imputation. The main outcomes were changes in positive and negative emotions, with moderation analysis assessing the interaction between optimism levels and response expectancies. The study adhered to the CONSORT guidelines.ResultsWhile no significant interaction was found between experimental conditions and time regarding emotional outcomes (p ˃ 0.05), moderation analysis revealed differential interactions between optimism levels and expectancies, particularly influencing positive emotions (p < 0.009). For participants with low optimism, positive emotions significantly increased from post-intervention to follow-up in the PC (t = −2.42, p < 0.016) and from pre-intervention to post-intervention in the ANC (t = 2.41, p < 0.018). Participants with medium optimism experienced an increase in positive emotions across all conditions from pre-intervention to follow-up and from post-intervention to follow-up (ps < 0.05). High optimism participants showed an increase in positive emotions from pre-intervention to follow-up and post-intervention to follow-up in the PC (t = 2.09, p < 0.038 and t = 3.06, p < 0.003) and NEC c (t = −2.76, p < 0.006 and t = 2.74, p < 0.007).ConclusionOur findings emphasize the effectiveness of a brief gratitude journal and underscore the nuanced role of response expectancy, especially in interaction with the initial level of optimism, in enhancing positive emotions. These results hold significance for both theoretical understanding and clinical applications.

White Grape Pomace Effect on Laying Hens’ Productivity, Egg Quality Traits, and Antioxidant Capacity Under Normal, Heat, and Cold Thermal Conditions

This study investigated the effect of white grape pomace (WGP) via a 6% level dietary supplementation on laying hens exposed to varying thermal stress conditions. The experiment was designed as a 2 × 3 factorial study, incorporating two dietary treatments (C and E) and three different thermal conditions: normal (NT: 22 °C), high stress (HST: 35 °C), and low stress (LST: 10 °C). Feed and water were provided ad libitum throughout the experiment. Results showed that the inclusion of 6% WGP in laying hens’ diet did not demonstrate beneficial effects under HST conditions, but under LST conditions, the WGP showed higher final body weight (1849.38 g) compared to both groups from the HST conditions (C 1599.40 g and WGP 1592.59 g), and the AEW (average egg weight) was highly significantly higher (p = 0.0001) compared to the C or NT groups (both groups, 2nd week), and the HST conditions (both groups, 2nd, 4th, and 6th weeks). HDEP (hen-day egg production) registered highly significant values (p = 0.0001) for the WGP group under HST conditions compared to HST conditions (both groups, 4th and 6th weeks). The whole egg weight was highly significant (p = 0.0001) for the WGP group under LTS conditions compared to the C group and to HST conditions (both groups, 2nd week and 6th week). The yolk weight parameter registered highly significant (p = 0.0001) values for the WGP group under LTS conditions compared to the C group and HST conditions (both groups, 2nd week; C group, 4th week; both groups 6th week) and the NT conditions (C group, 2nd week). Our study indicates that dietary supplementation with 6% white grape pomace (WGP) has potential benefits in LST conditions but limited efficacy under HST conditions. Further research is needed to explore the mechanisms and optimal inclusion levels of WGP in diets for laying hens exposed to different temperatures, especially in HST conditions.

Variation of Some Agro-Physiological and Biochemical Parameters of Wheat (Triticum aestivum L.) Varieties in Response to Nitrogen Fertilizer Rates at Djirataoua in Southern Niger Republic

Nitrogen is the most limiting plant nutrient element of soils in Niger. Farmers apply nitrogen to increase yield of cereal crops. A survey conducted at Djirataoua in southern Niger, revealed that wheat growers applied nitrogen fertilizer with less technical knowledge resulting in low response on growth and yield. To produce suitable recommendations to farmers, a field experiment was conducted during two dry seasons (2016/2017 and 2017/2018) at Djirataoua (13°25’59’’N, 7°8’12’’E). The aim of the study was to determine the optimum level of Nitrogen for highest yield and agro-physiological parameters of wheat varieties. Four Nitrogen levels (0, 100, 150 and 200 kg N ha-1) and four wheat varieties were evaluated in this study. The experiment was laid out in a split plot design with three replications. Data collected on grain yield, chlorophyll, Nitrogen uptake and protein content were subjected to the analysis of variance and mean comparison. The results showed that application of 150 kg N ha-1 Nitrogen resulted in highest grain yield (3202 kg ha-1), chlorophyll content (50.9 SPAD) N uptake (72.63 kg ha-1), and protein content (135.5 g kg-1). The wheat varieties were significantly different in these parameters. Reyna-28 and Sokoll/3/ produced higher grain yield and Nitrogen uptake. Higher protein content was observed in Norman and Sokoll/3/. Significant interactions were observed between Nitrogen rates and variety on yield characters, Nitrogen uptake and protein content. The highest grain yield, Nitrogen uptake and chlorophyll content were achieved by interaction of Reyna-28 and Sokoll/3/ with 150 kg N ha-1. Therefore, application of 150 kg N ha-1 and using varieties Reyna-28 or Sokoll/3/ is recommended to farmers for maximum grain yield and high protein content.

Dynamic Asset Allocation and Retirement Decision with Consumption Ratcheting and Effort Choice

This study examines the problem of choosing optimal consumption, investment, early retirement, and effort levels for an economic agent who is unwilling to reduce their consumption over time. The agent’s income depends on a fixed wage rate, and varies proportionally with their level of effort, which incurs disutility due to labor. By applying the dual-martingale method, we reformulate the problem into its dual form, dividing it into two distinct sub-problems: one focuses on selecting a consumption path that does not decrease, while the other determines the optimal timing for early retirement. Using this method, we find optimal strategies in the form of explicit closed-form solutions.

Methylthio Substituent in SAM Constructing Regulatory Bridge with Photovoltaic Perovskites

Inverted (p‐i‐n) perovskite solar cells (PSCs) have experienced remarkable advancements in recent years, which is largely attributed to the development of novel hole‐transport layer (HTL) self‐assembled monolayer (SAM) materials. Methoxy (MeO‐) groups are typically introduced into SAM materials to enhance their wettability and effectively passivate the perovskite buried interface. However, MeO‐based SAM materials exhibit a mismatch in highest occupied molecular orbital (HOMO) levels with perovskite layer due to the strong electron‐donating capability of methoxy group. In this work, we introduced a methylthio (MeS‐) substituent that is superior to methoxy as a highly versatile self‐assembled molecular design strategy. As a soft base, sulfur atom forms a stronger Pb‐S bond than oxygen. Additionally, within the CbzPh series of SAM materials, MeS‐CbzPh demonstrates a more optimal HOMO level and enhanced hole transport properties. Consequently, the MeS‐CbzPh HTL based device achieved an impressive power conversion efficiency (PCE) of 26.01% and demonstrated high stability, retaining 93.3% efficiency after 1000 hours of maximum power point tracking (MPPT). Moreover, in comparison with the commonly used 4PACz‐based SAM molecular series, MeS‐4PACz also exhibited the best performance among its peers. Our work provides valuable insights for the molecular design of SAM materials, offering a highly versatile functional substituent group.

Past-performance-driven strategy updating promote cooperation in the spatial prisoner's dilemma game

Strategy update rules play an important role in repeated Prisoner's Dilemma games. This work proposes a modified strategy update rule based on the traditional Fermi function, in which individual past performance is taken into account in strategy update. Then, the consistency aspiration α serves as a benchmark to measure an individual's past performance, and the past performance score is dynamically adjusted during the evolution process according to the BM reinforcement learning rules. The computational results indicate that the proposed modified strategy update rules can significantly improve system cooperation t than the traditional version, and the network reciprocity effect is enhanced as the result of past performance is coupled into the strategy update rule. Moreover, different temptation to defection b exist a corresponding aspiration α result in maximizing system cooperation. Furthermore, an optimal sensitivity level β can also result in a maximizing system cooperation. As a whole, for α − β phase diagram, different a will correspond to an optimal value β that allows the system to achieve the maximum cooperation. Finally, the proposed mechanism is robust. Hopefully this can help to inspire further research on how to deal with social dilemmas.

Methylthio Substituent in SAM Constructing Regulatory Bridge with Photovoltaic Perovskites

Inverted (p‐i‐n) perovskite solar cells (PSCs) have experienced remarkable advancements in recent years, which is largely attributed to the development of novel hole‐transport layer (HTL) self‐assembled monolayer (SAM) materials. Methoxy (MeO‐) groups are typically introduced into SAM materials to enhance their wettability and effectively passivate the perovskite buried interface. However, MeO‐based SAM materials exhibit a mismatch in highest occupied molecular orbital (HOMO) levels with perovskite layer due to the strong electron‐donating capability of methoxy group. In this work, we introduced a methylthio (MeS‐) substituent that is superior to methoxy as a highly versatile self‐assembled molecular design strategy. As a soft base, sulfur atom forms a stronger Pb‐S bond than oxygen. Additionally, within the CbzPh series of SAM materials, MeS‐CbzPh demonstrates a more optimal HOMO level and enhanced hole transport properties. Consequently, the MeS‐CbzPh HTL based device achieved an impressive power conversion efficiency (PCE) of 26.01% and demonstrated high stability, retaining 93.3% efficiency after 1000 hours of maximum power point tracking (MPPT). Moreover, in comparison with the commonly used 4PACz‐based SAM molecular series, MeS‐4PACz also exhibited the best performance among its peers. Our work provides valuable insights for the molecular design of SAM materials, offering a highly versatile functional substituent group.

Comparative Analysis of Silicone Mouth Swabs with Varying Hardness Levels for Optimal Plaque Removal in Elderly Oral Care.

Silicone mouth swabs have emerged as a promising alternative to gauze, sponge brushes, and soft-bristled toothbrushes, offering a balance between gentle cleaning and effectiveness. The flexibility and softness of silicone make it a suitable material for safely cleaning the sensitive oral tissues of elderly patients. This study aims to determine the optimal hardness level of silicone that maximises cleaning effectiveness while minimising the risk of trauma to oral tissues. A pseudo-plaque was created by mixing 6.0 g of Thicken Up Clear food additive with 12.0 ml of water and food colouring, which was then spread onto a NISSIN dentoform silicone rubber sheet (simulated soft tissue) with a thickness of 2.0 mm. Silicone heads with different hardness levels - 20, 30, 40, 50, and 60 Shore A - were attached to a V.P.2000 tooth brushing machine, operating at 75 rounds per minute with a force of 1.96 N. Each swab was used to brush the surface 25 times (n = 16 for each group). A one-way analysis of variance (ANOVA) revealed a statistically significant difference in pseudo-plaque removal among the five hardness levels, with an F-value of 106.161 (degrees of freedom = 4, 75, p 0.001). The Games-Howell pairwise comparison test showed that all five silicone hardness levels differed significantly from each other in their effectiveness in removing pseudo-plaque (p 0.05). No visible simulated soft tissue damage was observed before and after brushing, as inspected with a stereomicroscope in all experiments. The silicone oral swab with a hardness level of 60 Shore A was found to maximise pseudo-plaque removal in vitro. This finding is crucial for the development of specialised oral hygiene tools tailored to the needs of the elderly population, thereby enhancing oral health and overall well-being.

Stable developmental patterns of gene expression without morphogen gradients

Gene expression patterns in developing organisms are established by groups of cross-regulating target genes that are driven by morphogen gradients. As development progresses, morphogen activity is reduced, leaving the emergent pattern without stabilizing positional cues and at risk of rapid deterioration due to the inherently noisy biochemical processes at the cellular level. But remarkably, gene expression patterns remain spatially stable and reproducible over long developmental time spans in many biological systems. Here we combine spatial-stochastic simulations with an enhanced sampling method (Non-Stationary Forward Flux Sampling) and a recently developed stability theory to address how spatiotemporal integrity of a gene expression pattern is maintained in developing tissue lacking morphogen gradients. Using a minimal embryo model consisting of spatially coupled biochemical reactor volumes, we study a prototypical stripe pattern in which weak cross-repression between nearest neighbor expression domains alternates with strong repression between next-nearest neighbor domains, inspired by the gap gene system in the Drosophila embryo. We find that tuning of the weak repressive interactions to an optimal level can prolong stability of the expression patterns by orders of magnitude, enabling stable patterns over developmentally relevant times in the absence of morphogen gradients. The optimal parameter regime found in simulations of the embryo model closely agrees with the predictions of our coarse-grained stability theory. To elucidate the origin of stability, we analyze a reduced phase space defined by two measures of pattern asymmetry. We find that in the optimal regime, intact patterns are protected via restoring forces that counteract random perturbations and give rise to a metastable basin. Together, our results demonstrate that metastable attractors can emerge as a property of stochastic gene expression patterns even without system-wide positional cues, provided that the gene regulatory interactions shaping the pattern are optimally tuned.

An examination of the relationship between burnout and grit in college athletes

Burnout symptoms are a detrimental concern many athletes have at some point throughout their athletic careers. In order to assist athletes with performing at their optimal level, there is a need to better understand the burnout phenomena and the ways it can interact with other performance variables, such as grit. Given that grit is a predictor of success in a variety of domains (e.g., Duckworth & Yeager, 2015; Eskreis-Winkler et al., 2014; Fernández-Martin et al., 2020), the purpose of the study was to examine the relationship between grit and burnout. It was hypothesized that there would be an inverse correlation between grit and burnout. Grit and burnout data was collected from Division I student-athletes (n = 241) towards the end of their competitive seasons. Further, the student-athletes year in college was considered as a potential moderator between grit and burnout. The results indicated that student-athletes who scored higher in grit, also scored higher in burnout, hence the hypothesis was not supported. Additionally, there was a stronger positive relationship between grit and burnout for first-year students and sophomores, when compared with juniors and seniors. It is plausible athletes who are grittier are more likely to persevere through stress and challenges, including burnout symptoms, especially during their first two years of college. Athletes higher in grit may also be investing more effort into their sport, which could be increasing symptoms of burnout, as well. The results of this study warrant further investigation to clarify the interaction between grit and athlete burnout.

Experimental investigation and optimization of one-part alkali-activated self-compacting concrete mixes

Emphasizing the growing importance of sustainability, alkali-activated materials (AAMs) have emerged as a revolutionary alternative for cement in the construction sector. This study delves into the fresh, mechanical, and microstructural properties of One-Part Alkali-activated Self-compacting Concrete (OPASC) mixes. While mixtures of Ground Granulated Blast Furnace Slag (GGBFS) and Fly Ash (FA) were utilized as the precursors, powdered sodium metasilicate was employed to function as the activator. To streamline experimental design and reduce the economic demands of extensive testing, the Taguchi-Grey Relational Analysis (GRA) was utilized to identify optimal multi-response parameter levels. This method considered binder content (B) within a range of 700–800kg/m³, water-to-binder (W/B) ratios between 0.38 and 0.42, and Na2O percentages from 5% to 7% as key input variables. Results indicated that the designed mixes recorded workability values satisfying the EFNARC guidelines, compressive strengths greater than 60MPa, split-tensile strengths in the range of 3.5-4.6MPa, and flexural strengths varying between 5.5-7.2MPa. The mix parameters for the optimal mix, with the highest mean grey relational grade, were identified from the Taguchi-GRPA approach as B = 750kg/m3, W/B = 0.4, and N = 6%. Microstructural analysis revealed the formation of C/N-A-S-H type gels, which are instrumental in developing a compact matrix enhancing the mechanical properties. A good agreement between actual experimental results obtained for a different set of verification mixes with those predicted by regression-equations confirmed the potency of the Taguchi-GRA approach in optimizing the OPASC mix parameters.

A data-driven optimization model for the scattered storage assignment with replenishment

Modern warehouses are transitioning from pure storage facilities to order fulfillment centers. To improve order-picking efficiency, picking areas are restricted to small zones to save picker travel distance and thus can only store a limited quantity of SKUs. As a result, replenishment must be frequently carried out which not only causes intensive working efforts but also impacts the order-picking efficiency. Despite of the important role of replenishment, it has been seldom considered in storage assignment planning. This paper proposes a novel optimization model for the storage assignment problem considering both the order-picking and replenishment operations. Instead of the traditional first-extract-then-optimize paradigm, we develop an effective solution method for the problem by integrating the extraction and optimization steps together to avoid the loss of information. Intensive experiments and a case study are presented, the results of which indicate significant advantages of our model against the state-of-the-art counterpart. Several managerial implications are derived: (1) Order data implies substantial useful information for storage assignment planning, including but not limited to the demand correlation of products; (2) The replenishment efforts are intensive and negatively correlated to the order-picking efforts, which therefore should not be neglected in storage assignment planning; (3) To minimize the total working efforts, the optimal replenishment level r of the (r,S) replenishment policy should be more than 0.4S but less than 0.6S with respect to each SKU.

Performance improvement by an optimum companding-based Non-Uniform quantization scheme in low-bit resolution IMDD-UFMC system

In this paper, an optimum non-uniform quantization method is presented in the intensity-modulated direct detection universal filter multicarrier (IMDD-UFMC) system to achieve the system performance improvement with low-bit resolution digital-to-analog converter (DAC). By this specifically-designed companding quantizer without the probability density function (PDF) estimation, the number and interval size of the quantization interval allocated in the low probability region and the high probability region can be balanced with a modified optimal mapping relationship to obtain the optimal quantized level and then the low quantization noise is realized to greatly reduce the bit resolution of DAC in IMDD-UFMC system. Owing to this scheme is essentially a peak-to-average power ratio (PAPR) suppression technology of signal distortion, PAPR performance can be improved at the same time. Compared to the clustering and nonlinear programming schemes, the system performance in term of bit error rate (BER) can be improved and the difficulty of implementation can be reduced in the 25-Gb/s transmission system through 20-km fiber transmission. Moreover, a simplified method is presented by fitting the corresponding companding curve with error function and logistic function, which further decreases the complexity of the optimal non-uniform quantization. In this way, our scheme can offer a significant advancement in the design of IMDD-UFMC systems and has the potential to enhance the performance of future multi-carrier optical communication systems.

Does corporate board gender diversity influence shareholder value?

This study investigates the influence of board gender diversity on the shareholder value of South African-listed non-financial companies on the JSE from 2013 to 2022. The study used a quantitative quasi-experimental method to examine the influence of board gender diversity on shareholder value creation measures from a multi-theoretical perspective. The board gender diversity measures include the proportion of women directors on the board, the Blau index for board gender diversity, and dummy variables indicating the presence of one, two, three, or more women directors on the board, as well as skewed board, tilted board, and balanced board. Shareholder value creation is proxied using standardised market value added, market-to-book ratio, and Tobin’s Q. The study utilises fixed effects models based on linear and curvilinear models to test the hypotheses. According to linear models, all board gender diversity measures demonstrate a significant positive, negative, or no effect on shareholder value creation measures, aligning with the multi-theoretical perspective of corporate governance research. However, curvilinear quadratic models suggest that the Blau index for board gender diversity and the proportion of women directors on board positively and negatively affect shareholder value creation, highlighting an inverted U-shaped effect. The results recognise the "too much- of- a -good- thing” effect and a possible optimal(or worse) level of board gender diversity as crucial. In conclusion, this study demonstrates that the claim of the ‘‘one size fits all’’ board gender diversity mechanism in creating and maximising shareholder value, often implicitly stated by regulators and advisors, may be misleading.

Optimizing Palm Oil Production Scheduling In Nigeria Using Balanced Transportation Problem

This paper deal with optimizing palm oil production of a production firm in Nigeria using balanced Transportation problem in other to reduce or increase/ minimize the production cost and increase or maximize production, profit and efficiency. Here the scheduling challemnge is developed and modeled as a balanced of transportation problem as requires in creation of an optimum production schedule. This resulted in allocating optimal and maximum production level such that the given demand were meet at a minimum cost .

A novel linear programming-based predictive control method for building battery operations with reduced cost and enhanced computational efficiency

Battery energy storage systems can be readily integrated with buildings to enhance renewable energy self-consumptions while leveraging time-variant electricity tariffs for possible operation cost reductions. The extensive variability in building operating conditions presents significant challenges in developing universally applicable methods for optimal controls. To ensure reliable and robust controls, this study integrates predictive control with efficient linear programming to effectively fine-tune battery controls for real-time operations. An adaptive time aggregation scheme has been proposed to streamline the optimization process by accounting for unique changes in energy balances and tariffs. Comprehensive data experiments, based on measurements from 95 unique building operation scenarios, have been conducted to quantify the control performance given different optimization formulations, varying types and levels of prediction uncertainties in building energy demands and PV generations. The results validate the value of the method proposed, leading to 11.75% to 34.63% operation cost reductions on average, while reducing computation steps by 87.75% to 92.60% compared with conventional linear programming approaches. The insights obtained are useful for developing flexible building control strategies with improved computation efficiency and robustness, while providing extensible optimization frameworks for buildings with various energy patterns and storage systems.

Identification of the enzyme activity of human Demodex aspartic protease and its function to hydrolyse host macromolecules and skin cell proteins

Aspartic protease (ASP), a common proteolytic enzyme, plays an important role in the pathogenesis of numerous parasites. However, its role in Demodex remains unclear. Herein, we studied the expression, purification, enzymatic activity detection, and hydrolysis function of human Demodex ASP. The findings showed that recombinant ASP (rASP) possessed aspartic protease activity, which reached optimum levels at pH 2.5–3.0 and 35 °C. Furthermore, the activity of Demodex folliculorum rASP (Df. ASP) was considerably higher than that of Demodex brevis rASP (Db.rASP). Df.rASP also exhibited a more potent hydrolytic ability than Db.rASP. Df.rASP hydrolysed IgG, IgM, and fibronectin, whereas Db.rASP only slightly hydrolysed IgG. Mass spectrometry analysis revealed that Df.rASP exerted hydrolytic effects on 38 HaCaT proteins, more than the 23 proteins hydrolysed by Db.rASP. Sequence alignment and structure modelling of the substrate binding cleft identified three distinct amino acids between Df. ASP and Db. ASP, which should be the molecular basis for their difference in enzymatic activity and hydrolytic function. These results imply that Df.rASP may play a more critical role in the pathogenesis of human Demodex, and molecular data will provide a scientific basis for future analyses of their molecular pathogenesis.

Optimisation Studies on Performance Enhancement of Spray Cooling - Machine Learning Approach

The performance optimisation of spray cooling heat transfer systems has been identified as a significant step in improving process efficiency, and the application of machine learning tools is a recent development that has enhanced this. This study aims to maximise the heat transfer coefficient for spray cooling at low heat flux levels. The effects of nozzle inclination angle, water pressure, and spray height on heat transfer coefficient were studied. Taguchi L27 orthogonal array technique was used to perform the experiments. A maximum heat transfer coefficient of 181.4 kW/m2K was obtained at a nozzle inclination angle of 60o, spray height of 4 cm, and water pressure of 15 psi. Analysis of variance was performed to find the significance of each variable and its interactions. The results show that for the maximum heat transfer coefficient (181.4 kW/m2K), the optimum levels of the independent variables were A3H1P3, i.e., the highest level of nozzle inclination angle (60o), the lowest level of spray height (4 cm), and the highest level of water pressure (15 psi). The support vector machine outperformed the Random Forest algorithm and Multiple Regression analysis regarding prediction accuracy with a maximum error of 0.15% and root mean squared error of 0.01.

Influence of the use of ground enhancement materials on the reduction of electrical resistivity in grounding systems: a review

A grounding system (GS) is an indispensable component in an electrical system network, as it is responsible for conducting electrical discharges to the ground due to faults caused by lightning strikes or transient system failures. Globally, it is estimated that 40 lightning strikes occur per second on the planet, amounting to around 1.2 billion per year, resulting in daily losses of various electrical equipment and human fatalities ranging from 6,000 to 24,000. Additionally, soil resistivity, which impedes the flow of electricity from electrical discharges into the ground, leads to inadequate mitigation of electrical overload effects, resulting in poor GS performance. Consequently, the implementation of ground enhancement materials (GEMs) to reduce impedance to optimal levels becomes necessary. The objective of this review is to broadly examine the current status of GEMs reported in the literature for use in GS, focusing on their composition and their effectiveness in improving soil conductivity and dissipating electrical currents as well as to identify emerging trends and current challenges in the development and application of these materials, in order to provide information to guide future research in the design and implementation of efficient and safe GS.