Optimal Shift Research Articles

Combined effect of temperature and total solid content on methane yield: Balancing hydrolysis and methanogenesis

The hydrolysis rate is enhanced by temperature and total solid (TS) content during anaerobic digestion (AD). However, methanogenesis can be easily inhibited under these same conditions. Therefore, a balance point may exist between hydrolysis and methanogenesis by regulating these parameters. This study explored the AD of chicken manure and corn straw at different temperatures (35℃, 45℃, and 55℃) and TS contents (6%, 8%, 10%, and 12%). Results indicate that as TS content increases, the optimum temperature shifts from thermophilic to mesophilic. This could be explained by excessive hydrolysis under higher temperatures and TS may hinder methanogenesis due to ammonia accumulation. At 8% TS, 45°C achieves the highest methane production, challenging the notion that this temperature range lacks efficient gas production. This indicated that the optimal temperature is not fixed and should be evaluated alongside other operational parameters, especially in industrial AD. Elevated temperatures and higher TS content boosted glycolysis metabolism, amino acid metabolism, and hydrogenotrophic pathways but restricted pyruvate metabolism and acetoclastic methanogenesis, leading to reduced methane production. Compared to bacterial adaptation, methanogens showed less resilience to environmental changes.

Re-assessing thermal response of schistosomiasis transmission risk: Evidence for a higher thermal optimum than previously predicted.

The geographical range of schistosomiasis is affected by the ecology of schistosome parasites and their obligate host snails, including their response to temperature. Previous models predicted schistosomiasis' thermal optimum at 21.7°C, which is not compatible with the temperature in sub-Saharan Africa (SSA) regions where schistosomiasis is hyperendemic. We performed an extensive literature search for empirical data on the effect of temperature on physiological and epidemiological parameters regulating the free-living stages of S. mansoni and S. haematobium and their obligate host snails, i.e., Biomphalaria spp. and Bulinus spp., respectively. We derived nonlinear thermal responses fitted on these data to parameterize a mechanistic, process-based model of schistosomiasis. We then re-cast the basic reproduction number and the prevalence of schistosome infection as functions of temperature. We found that the thermal optima for transmission of S. mansoni and S. haematobium range between 23.1-27.3°C and 23.6-27.9°C (95% CI) respectively. We also found that the thermal optimum shifts toward higher temperatures as the human water contact rate increases with temperature. Our findings align with an extensive dataset of schistosomiasis prevalence in SSA. The refined nonlinear thermal-response model developed here suggests a more suitable current climate and a greater risk of increased transmission with future warming for more than half of the schistosomiasis suitable regions with mean annual temperature below the thermal optimum.

Immobilization and characterization of hormone-sensitive lipase (HSL) from Glaciozyma antarctica

HSL-like esterase (GlaEst12) was isolated from the psychrophilic yeast Glaciozyma antarctica, and has a broad substrate specificity hence allowing hydrolysis of a wide range of ester molecules. This characteristic makes it relevant in a variety of industries, including food processing, pharmaceutical, and bioenergy. Immobilization of HSL-like esterase from G. antarctica (GlaEst12) was achieved through physical adsorption onto different types of supports such as Amicogen LKZ118, Amicogen LKZ518, Accurel MP1000, Seplite LXC621, and Seplite LX120. Among these, LKZ518 and LX120 exhibited a high immobilization rate (95 - 100 %), surpassing the other tested supports. Nonetheless, their recorded enzyme activity was notably lower when contrasted with the activity observed on LKZ118. While LKZ118 displayed a 50 % immobilization rate, it demonstrated remarkably high enzyme activity compared to the other supports. The optimal enzyme concentration for immobilization was determined to be 5 mg per gram of LKZ118 support. The immobilized lipase (GlaEst12_LKZ118) showed an optimum temperature et 60 °C similar to free GlaEst12 when tested using pNP-octanoate substrate. However, it showed a shift in pH optimum from pH 8 for free GlaEst12 to pH 9 for GlaEst12_LKZ118. GlaEst12_LKZ118 demonstrated prolonged stability at 60 °C, with a half-life of 180 min. Furthermore, it exhibited stability in the presence of methanol when treated at 50 °C, and increased activity in the presence of DMSO. Operational stability tests revealed that GlaEst12_LKZ118 maintained 65.5 % of its relative activity after 7 cycles, indicating its robust operational stability. In summary, the study demonstrated the successful immobilization of HSL lipase derived from G. antarctica using various supports and the immobilized enzyme showed promising activity levels for potential applications in biodiesel production and flavour ester synthesis.

Significant shifts in latitudinal optima of North American birds

Changes in climate can alter environmental conditions faster than most species can adapt. A prediction under a warming climate is that species will shift their distributions poleward through time. While many studies focus on range shifts, latitudinal shifts in species' optima can occur without detectable changes in their range. We quantified shifts in latitudinal optima for 209 North American bird species over the last 55 y. The latitudinal optimum (m) for each species in each year was estimated using a bespoke flexible non-linear zero-inflated model of abundance vs. latitude, and the annual shift in m through time was quantified. One-third (70) of the bird species showed a significant shift in their optimum. Overall, mean peak abundances of North American birds have shifted northward, on average, at a rate of 1.5 km per year (±0.58 SE), corresponding to a total distance moved of 82.5 km (±31.9 SE) over the last 55 y. Stronger poleward shifts at the continental scale were linked to key species' traits, including thermal optimum, habitat specialization, and territoriality. Shifts in the western region were larger and less variable than in the eastern region, and they were linked to species' thermal optimum, habitat density preference, and habitat specialization. Individual species' latitudinal shifts were most strongly linked to their estimated thermal optimum, clearly indicating a climate-driven response. Displacement of species from their historically optimal realized niches can have dramatic ecological consequences. Effective conservation must consider within-range abundance shifts. Areas currently deemed "optimal" are unlikely to remain so.

Impacts of host availability and temperature on mosquito‐borne parasite transmission

AbstractGlobal climate change is predicted to cause range shifts in the mosquito species that transmit pathogens to humans and wildlife. Recent modeling studies have sought to improve our understanding of the relationship between temperature and the transmission potential of mosquito‐borne pathogens. However, the role of the vertebrate host population, including the importance of host behavioral defenses on mosquito feeding success, remains poorly understood despite ample empirical evidence of its significance to pathogen transmission. Here, we derived thermal performance curves for mosquito and parasite traits and integrated them into two models of vector–host contact to investigate how vertebrate host traits and behaviors affect two key thermal properties of mosquito‐borne parasite transmission: the thermal optimum for transmission and the thermal niche of the parasite population. We parameterized these models for five mosquito‐borne parasite transmission systems, leading to two main conclusions. First, vertebrate host availability may induce a shift in the thermal optimum of transmission. When the tolerance of the vertebrate host to biting from mosquitoes is limited, the thermal optimum of transmission may be altered by as much as 5°C, a magnitude of applied significance. Second, thresholds for sustained transmission depend nonlinearly on both vertebrate host availability and temperature. At any temperature, sustained transmission is impossible when vertebrate hosts are extremely abundant because the probability of encountering an infected individual is negligible. But when host biting tolerance is limited, sustained transmission will also not occur at low host population densities. Furthermore, our model indicates that biting tolerance should interact with vertebrate host population density to adjust the parasite population thermal niche. Together, these results suggest that vertebrate host traits and behaviors play essential roles in the thermal properties of mosquito‐borne parasite transmission. Increasing our understanding of this relationship should lead us to improved predictions about shifting global patterns of mosquito‐borne disease.

Shear rheology senses the electrical room-temperature conductivity optimum in highly Li doped dinitrile electrolytes.

Glutaronitrile (GN) doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at concentrations below and above the room-temperature conductivity optimum near 1M of Li salt is investigated using dielectric spectroscopy and shear rheology. The experiments are carried out from ambient down to the glass transition temperature Tg, which increases considerably as LiTFSI is admixed to GN. As the temperature is lowered, the conductivity optimum shifts to lower salt concentrations, while the power-law exponents connecting resistivity and molecular reorientation time remain smallest for the 1M composition. By contrast, the rheologically detected time constants, as well as those obtained using dielectric spectroscopy, increase monotonically with increasing Li salt concentration for all temperatures. It is demonstrated that the shear mechanical measurements are, nevertheless, sensitive to the 1M conductivity optimum, thus elucidating the interplay of the dinitrile matrix with the mobile species. The data for the Li doped GN and other nitrile solvents all follow about the same Walden line, in harmony with their highly conductive character. The composition dependent relation between the ionic and the reorientational dynamics is also elucidated.

Best of both worlds: Acclimation to fluctuating environments confers advantages and minimizes costs of constant environments

Abstract Thermal acclimation is often considered critical in organismal responses to novel thermal conditions. Our understanding of the physiological implications of acclimation is largely derived from lab studies that either manipulate daytime basking availability or use of constant thermal regimes. In contrast, the importance of the nocturnal thermal environment (e.g. the extent of thermal respite) is often overlooked yet could play a vital role in thermal acclimation in the wild. To fill this gap, we acclimated lizards (Amphibolurus muricatus) under three thermal regimes (Hot Constant, Cold Constant and Alternating) and compared their physiological responses (Metabolic Rate, Sprint Speed, Thermal Preferences and Thermal Limits). We found that animals maintained constantly at hot temperatures (preferred temperature, 35°C) gained sprint performance increases and exhibited shifts in thermal optima not seen in those maintained constantly at cold temperatures (20°C), yet suffered costs to growth (in smaller animals) and maintenance (mass loss in larger animals). Animals maintained at alternating temperatures (12 h 20°C; 12 h 35°C) had performance benefits similar to animals in the hot treatment, without experiencing reductions in juvenile growth and adult mass. Animals acclimated under hot temperatures showed a significant lower preferred and voluntary maximum temperatures compared to animals acclimated under a cold temperature regime. We found no impact of acclimation treatment on behavioural thermal limits or standard metabolic rate. Overall, we show that alternating between access to preferred temperatures and having periods of energetic rest confer the greatest benefits for our animals. These results highlight the importance of natural body temperature variation for enhancing overall ectotherm performance and physiology, and the costs of novel thermal environments that fail to provide this variation. Read the free Plain Language Summary for this article on the Journal blog.

Enhancing security for physical layer communication in RIS-aided MIMO-NOMA systems in the presence of an eavesdropper

This paper investigates the potential of leveraging a reconfigurable intelligent surface (RIS) in the multiple-input multiple-output non-orthogonal multiple access (MIMO-NOMA) wireless communication systems. In fact, NOMA improves spectral efficiency (SE) through power domain utilization, and RIS enhances the system performance by manipulating the propagation environment. In this paper, we investigate the physical layer security (PLS) of a RIS-aided MIMO-NOMA system serving two users in the presence of an eavesdropper (EV), where the channel state information (CSI) of the EV is unknown for the BS. To address the security challenge, we utilize secrecy outage probability (SOP) and minimize it by optimizing the RIS’s phase shift matrix, the beamforming vector, and the power allocation coefficients. Due to the non-convexity of the main optimization problem, we decompose the initial problem into three subproblems, and then, we propose an iterative approach to determine the unknown parameters alternately. The first subproblem involves obtaining the optimal beamforming vector and phase shift matrix using the semidefinite relaxation (SDR) method, which introduces high complexity. As an alternative, another algorithm is proposed based on the duality of the optimization problem, offering lower complexity and better accuracy for high-dimensional optimization problems. In this algorithm, the successive convex approximation (SCA) technique is employed to achieve the optimum phase shift matrix, and the stochastic gradient (SG) approach is used to determine the beamforming vector. Furthermore, the paper establishes the optimal values of power allocation coefficients by minimizing the difference between the SOPs of the two users. Finally, the simulation results demonstrate that the proposed power allocation coefficients scheme significantly enhances system performance compared to the existing fixed power allocation coefficients scheme.

Numerical study on throttling characteristics of RBCC engines in ejector mode

Investigating the throttling characteristics of Rocket-Based Combined Cycle (RBCC) engines in ejector mode is crucial for adapting to varied flight mission demands. This study employs validated RANS numerical methods to investigate throttling effects on an experimental kerosene-fueled RBCC engine under two representative flight conditions: ground take-off (Mach 0) and supersonic flight (Mach 2.0). Results indicate that, at Mach 0, throttling reduces the entrained secondary stream and increases mixing efficiency, but exacerbates mixing losses, which cannot be offset by the thrust produced by the secondary stream due to its weak working capacity. Therefore, specific impulse performance deteriorates during throttling. Moreover, the optimum mixture ratio remains at 2.4, consistent with conventional rockets. Conversely, at Mach 2.0, throttling mitigates the primary stream’s squeezing effect to augment the entrained secondary stream. Simultaneously, throttling enhances mixing efficiency to improve the utilization of residual fuel. Consequently, the optimum mixture ratio shifts from 2.4 to below 1.4, which contributes to harnessing the work capacity of the secondary stream generated by ram effects, and significantly improves specific impulse performance. This study emphasizes the distinct throttling characteristics at different Mach numbers and provides pivotal insights for developing more efficient RBCC engines in ejector mode.

Optimized absorption of light in perovskite nanowire solar cells

Metal halide perovskite nanowires (PrvNWs) have recently emerged as an interesting path for nanostructured solar cells. Here, we model the absorption of light in PrvNW arrays for varying diameter and length of the PrvNWs and period for the array by solving the Maxwell equations. For long enough bare PrvNW arrays, we find that the optimum diameter is fixed to that which places the absorption peak from the HE11 waveguide mode in the PrvNWs to the vicinity of the bandgap wavelength. In contrast, when we include a transparent conductive oxide (TCO) top contact layer, the optimum diameter shifts to a larger value by 100 nm. The origin of this shift is traced to a reduced reflection at the interface between the TCO layer and the PrvNW array when the PrvNW’s diameter is larger. Overall, we find that 1500 nm long PrvNWs can reach 90% of the broadband absorption potential, making this system of high interest for photovoltaics.

Climate bottlenecks off Newfoundland and Labrador for Atlantic cod in relation to eastern Canadian marine protected areas

Climate change presents challenges for marine area-based conservation measures through altered habitat and associated species range shifts. We conducted statistical downscaling for the eastern Canadian coastal domain over a range of global climate models, focusing on habitat suitability for Atlantic cod ( Gadus morhua), a numerically depressed, but ecologically, economically, and culturally important species in this region. We examined cod egg survival, juvenile growth, and spawning habitat suitability, combining these into one habitat index to compare within-closure habitat suitability for multiple life stages through time. Areas of high cod egg habitat suitability are projected to shift northward and increase across all area closures studied, while optimum juvenile habitat shifts north and eastward, increasing in almost all closures except the south. Spawning habitat as a function of temperature and oxygen will likely decrease through time across the entire region, but less in northern locations. Overall cod habitat is forecasted to decline in the south of the region while increasing at central and northern latitudes, highlighting the importance of existing and developing northern shelf area closures. While warming will bring temperatures closer to optimum levels for cod in this cold-water system, oxygen limitation will become more prevalent in the south of the region and should be monitored as an important ocean health indicator.

Development of a device to improve the precision of water surface identification for MeV electron beam dosimetry

The study aimed to develop a laser-based distance meter (LDM) to improve water surface identification for clinical MeV electron beam dosimetry, as inaccurate water surface determination can lead to imprecise positioning of ionization chambers (ICs). The LDM consisted of a laser ranging sensor, a signal processing microcontroller, and a tablet PC for data acquisition. I50 (the water depth at which ionization current drops to 50 % of its maximum) measurements of electron beams were performed using six different types of ICs and compared to other water surface identification methods. The LDM demonstrated reproducible I50 measurements with a level of 0.01 cm for all six ICs. The uncertainty of water depth was evaluated at 0.008 cm with the LDM. The LDM also exposed discrepancies between I50 measurements using different ICs, which was partially reduced by applying an optimum shift of IC's point of measurement (POM) or effective point of measurement (EPOM). However, residual discrepancies due to the energy dependency of the cylindrical chamber's EPOM caused remained. The LDM offers straightforward and efficient means for precision water surface identification, minimizing reliance on individual operator skills.

Effect of wingtip bending morphing on gust-induced aerodynamics based on fluid-structure interaction method

This paper investigates the effect of wingtip bending morphing on gust-induced aerodynamics based on the fluid–structure interaction (FSI) method at Re = 40 000. First, an explicit spatiotemporal numerical model for a wingtip bending morphing on a wing with a semi-aspect ratio of 4 is deduced, considering geometrical nonlinearity under large morphing amplitude. A modal-based FSI framework is developed to consider the elastic deformation, active wingtip morphing, and gust. The shear-stress transport-γ model is introduced. The above FSI method is validated by gust response experimental results. The mitigation effects of active bending morphing on gust-induced aerodynamics at different phase offset, gust ratios (GR), and flare angles are investigated. Under GR = 0.2 and flare angle = 0, wingtip bending morphing achieves the best mitigation effect when the phase offset is π/2. As GR increases to 0.4, the optimum phase offset shifts to π/3 and the alleviation rate decreases. The mitigation rate increases with the flare angle. Under GR = 0.4 and flare angle = 30°, the optimum phase offset is π/6, in which case the lift response is reduced by 37%, and wing root bending moment response is reduced by 73% relative to the baseline case. The flow field and vortex evolution result infers that the wingtip bending morphing decreases the spanwise width of the leading-edge vortex and reduces the area of low-pressure zones on the suction side, thereby mitigating gust-induced aerodynamics. The results indicate that active wingtip bending morphing has great potential for gust load alleviation for future aircraft.

Precise gamma-ray spectrum stabilization using full spectral information

One of the most important steps in recording, processing and analyzing gamma-ray spectra is stabilizing the measured spectrum. Baseline shifts and gain changes of any origin including environmental condition, high voltage instability and amplifying not only cause drifts in gamma-ray spectrum, but also force the spectrum to be noticeably distorted. In this work, a stabilization method based on full gamma-ray spectrum shape consideration is introduced for online as well as offline stabilization of gamma-ray spectra. The method relies upon sequentially comparing spectra, each measured during a time window, and subsequently finding the optimum shift for each time window using an artificial intelligence method aiming at minimizing the difference between the general shapes of the spectra. By utilizing spectra measured during shorter acquisition times and stabilizing them, a stable spectrum can be obtained for the longer acquisition time without the need to determine the detection system parameters, peak positions, or perform energy calibration. Subsequently, a sequence of stabilized spectra converging to the total stabilized spectrum is created. The proposed method has been applied to stabilize and analyze 14 MeV neutron induced prompt gamma-ray (PG) spectra of various samples measured using a 3 × 3 inch NaI detector. Additionally, the method has been used to stabilize the recorded spectra of 152Eu and 60Co gamma-ray point sources. The proposed method has efficiently stabilized all the tested gamma-ray spectra, resulting in a significant improvement of the analysis results.

An improved WiFi sensing based indoor navigation with reconfigurable intelligent surfaces for 6G enabled IoT network and AI explainable use case

The expanding number of low cost sensors and smart devices drives the internet-of-things (IoT) ecosystem of the future. These sensing devices are connected to the internet for information exchange. The location and positioning of these nodes is very important information required in vast range of location based services like smart homes, smart healthcare, environmental monitoring, personal navigation and smart transportation. This paper presents an intelligent solution for node localization in a 6G enabled IoT network. An indoor communication network scenario is proposed in which reconfigurable intelligent surfaces (RISs) are installed to locate the sensor nodes operating in that network. The performance evaluation of the proposed scheme is carried out with optimum number of reflecting elements and optimum phase shifts. It is observed that optimized RISs with 100 reflecting elements improve the estimated localization error by 7.4% over non-optimum RISs. Also, the minimum gain of 6% in localization error is offered using equal phase shifts over random phase shifts. Further, the effect of channel conditions on the average estimation error in node locations is also elaborated. In the end, the explainable artificial intelligence (XAI) empowered indoor localization is discussed as a use case scenario and the performance comparison of the algorithms is evaluated.

Predicted roundtrip efficiency for compressed air energy storage using spray-based heat transfer

Compressed air energy storage (CAES) is a low-cost, long-duration storage option under research development. Several studies suggest that near-isothermal compression may be achieved by injecting water droplets into the air during the process to increase the overall efficiency. However, little is known about the thermal-fluid mechanisms and the controlling nondimensional parameters of the expansion process, which has previously been assumed to mirror the compression process. Furthermore, the isothermal round-trip efficiency and the impact of spray-based CAES have not been investigated. This study uses a validated 1-D model for compression and expansion with spray injection to complete a parametric analysis to analyze the thermal-fluid time-dependent physics and resulting roundtrip isothermal efficiency of a CAES system. Comparing the results for compression and expansion simulations, compression is found to have a higher isothermal efficiency than expansion for the same set up. The polytropic index for both compression and expansion tends to decrease and approach the ideal isothermal limit as nondimensional mass loading increases and as nondimensional Crowe number (ratio of thermal response time to domain time) decreases. As such, the highest efficiency designs are those with slow compression speeds and high spray flow rates to achieve high mass loading and those with small droplets to achieve low Crowe numbers—as long as spray work is neglected. If spray work is included, the optimum spray conditions shift to those with lager drop sizes. For example, roundtrip isothermal efficiency peaks around 95 % at a mass loading of 14 and at Crowe numbers <0.1 with a pressure ratio of ten. The results indicate that near-isothermal CAES compression and expansion is possible but that spray work should be included for significant mass loadings (e.g. greater than unity). Further investigation is recommended to consider effects of multi-dimensionality, turbulence, wall-interactions, and droplet dynamics.

Microemulsion phase behavior of active live oil

Microemulsion phase behavior of live crude oil has been investigated at 1700 psi and 55 °C using an active crude oil with a total acid number of 1.18 mg-KOH/g-oil. The live crude oil was reconstituted by adding 36.0 mol% methane to dead crude oil. Sodium carbonate was used for a salinity scan, and also as an alkali to convert the acid components in crude oil to natural soap. The equivalent alkane carbon number (EACN) of dead crude oil was determined by measuring optimum salinity of dead crude oil and several surrogate crude oils diluted with pure n-alkanes. The optimum salinity of live crude oil was compared to those of dead and surrogate crude oils to determine the EACN of the live crude oil. To keep the surfactant pseudo-phase composition constant in the ternary phase diagram, the molar ratio of crude oil to synthetic surfactant was controlled. The natural soap and synthetic surfactant were kept the same for each volume ratio of crude oil to surfactant solution. The EACN of the crude oil was found to be independent of the soap-to-surfactant molar ratio, which means EACN is an intrinsic property of oil under the experimental conditions investigated. Based on the optimum salinity shift from dead crude oil to live crude oil, the compositional effect of methane with active crude oil was measured to be about the same as for inactive crude oil. The apparent EACN of methane was found to be equal to about 10.2. The solubilization ratio of the live oil at optimum salinity was greater than the value for the dead crude oil. The results indicate that the microemulsion phase behavior of live crude oil with acidic components can be interpreted using classical EACN concepts by the same criteria as that of inactive crude oil. Thus, the effect of the soap generation reaction can be decoupled from the physical interactions.

FROM AN AGROPHILE TO A SYNURBIST: HOW THE COMMON HAMSTER (&lt;i&gt;CRICETUS CRICETUS&lt;/i&gt;) IS SETTLING INTO THE URBAN ENVIRONMENT

In this review, using our own and published data, we discuss the processes that occur in populations of small mammals when they adapt to and master the urban environment, using the common hamster as an example. Originally, the common hamster was apparently associated with the forest-steppe zone, but with the development of agriculture, it became an agrophile, populating the outskirts of fields, which provided it with a good food base throughout the year. Changes in farming culture (fragmentary fields replaced with vast areas of arable land occupied by monocultures, the use of poisons and fertilizers) led to a shift in the ecological optimum of the species to areas occupied by gardens, kitchen gardens and urban ecosystems. This led to changes in the genetic structure of populations, a greater (compared to suburbs) diversity of alleles of the major histocompatibility complex responsible for resistance to pathogens, a reduced hibernation period up to its complete abandonment, and a reduced aggressiveness to conspecifics which allows for more burrows to be arranged in a limited space and for general food storages to be shared and consumed. The use of food wastes as an additional food resource by this species may have led to changes in its digestive and other systems. All of this has allowed the common hamster to successfully exist in an urbanized environment, despite the reduction in life expectancy due to many stressors (parasitic load, pollution etc.). It is assumed that not all of the above traits have been formed in the process of synurbization. Many adaptations acquired earlier, before urbanization, proved to be effective in its development of the urban environment. Obviously, the path taken by the common hamster from a non-commensal species to an agrophile, and finally a synurbist is not unique; many other species of mammals and birds have passed or are on this evolutionary path at the present time.

Optimizing human reliability in work shifts scheduling: A real case of clothing job shop

AbstractIn this research, we provide a mathematical model with an objective function of minimizing human errors for the problem of shift scheduling optimization. The unique aspects which are considered in our model are learning, forgetting, fatigue, and rest parameters (which affect the human reliability). Various problems with different human parameters, based on real cases of clothing job shops, are solved to study the efficiency and effectiveness of the optimization model. Two improved bacterial foraging algorithms are presented to handle the complexity of our problem. To examine the capability of the presented swarm intelligence algorithms in obtaining global optimum problem, we compare the results of the algorithms against the solution of basic bacterial foraging algorithm in terms of solutions quality. Results indicate that the solution approaches are more efficient in searching solution space and convergence. Analysis of different shift scheduling shows that in moderate fatigue condition, the scenario of scheduling with continuous work hours is better in terms of productivity. Also, experiments demonstrate that optimum reliable shift schedules are related to human factors. The findings of our research indicate that the presented scheduling model and improved algorithms can provide optimum shift schedules regarding human factors.

A new method to explicitly estimate the shift of optimum along gradients in multispecies studies

A new method to explicitly estimate the shift of optimum along gradients in multispecies studies