Research on cognitive load evaluation with subjective method in manual assembly

Subjective scales have different kinds of applicability in diverse fields.This study intends to implement a quantitative approach to determine the applicability of subjective scales in manual as-sembly work and evaluate the cognitive load of assembly workers.A multi-scale research paradigm based on subjective evaluation method is proposed.Three typical task stages are extracted from the process of assembly work.The National Aeronautics and Space Administration Task Load Index(NASA-TLX)scale,PAAS scale and Workload Profile Index Ratings(WP)scale are selected for the design of 3×3 multi-factor mixed experiment.The power spectrum density(PSD)characteris-tics of electroencephalogram(EEG)are utilized to identify the difficulty levels of the three task sta-ges.The relevant indicators of scale applicability are assessed.The results show that in terms of sensitivity,NASA-TLX scale reaches the highest sensitivity(F=999.137,P=0<0.05).In terms of validity,NASA-TLX scale possesses the best concurrent validity(P=0.0255<0.05).In terms of diagnosticity,NASA-TLX scale based on 6 dimensions takes on the best diagnostic performance.In terms of subject acceptability,WP scale performs the worst.According to the analytic hierarchy process(AHP)model,the applicability scores of NASA-TLX scale,PAAS scale and WP scale are determined as 3,2.55 and 1.6714,respectively.Therefore,NASA-TLX scale is regarded as the most suitable subjective evaluation questionnaire for assembly workers,which is also an effective quantitative evaluation method for the cognitive load of assembly workers.

Evolution of Sedimentation in a Headrace Canal for Hydroelectric Production Case of the Shongo Basin of the Inga Complex from February 2020 to May 2021 (Kongo Central Province/DR Congo)

The headrace of the Inga hydropower complex is experiencing siltation problems, reducing the exploitable draft and limiting the production capacity of the two main Inga hydropower plants during the low water period. During the 2019 low water period, several sediment slumps occurred in the Shongo basin, disrupting the production of hydroelectric power generated by the Inga 1 & 2 power plant, resulting in massive load shedding of power supply to downstream customers. The cardinal aim of this study is to determine the quantities of sediments deposited and those eroded, in order to know the evolution of sedimentation in the Shongo basin from February 2020 to May 2021. The results obtained show that the running index of the generating units is determinant and influences the sedimentation process in the Shongo basin. The cleaning of the Shongo basin in terms of the spatial distribution of sedimentation from February 2020 to May 2021 is plausible.

Evaluation of Environmental Carrying Capacity of Water Resources in Jiangxi Province

In order to quantitatively evaluate the sustainable development status of water resources in Jiangxi Province, the dynamic changes in ecological footprint, carrying capacity and load index of water resources in Jiangxi Province during 2009-2013 were analyzed according to the primary principle and calculation model of ecological footprint. The results showed that in Jiangxi Province during 2009- 2013, the water resources ecological footprint per capita was relatively low; the wa- ter resources utilization level was relatively low; the overall development potential of water resources was great; the water resources ecological carrying capacity per capita and ecological footprint per capita were trended to be increased overall. The changes in water resources ecological footprint are closely related to the social and economic development. Therefore, the industrial structure should be fully adjusted, and the water resources should be scheduled and utilized reasonably so as to pro- mote the protection of water resources and sustainable development of society and economic in Jiangxi Province.

Physico-chemical characteristics and heavy metal concentrations of copper mine wastes in Zambia:implications for pollution risk and restoration

Soil characterization is a vital activity to develop appropriate and effective restoration protocols for mine wastelands while insights into the total content of heavy metals in the soil is an important step in estimating the hazards that the metals may pose to the vital roles of soil in the ecosystem.This study addressed the following research questions:(1)To what extent do the physico-chemical characteristics vary between mine waste sediments and the nearby forest soil?(2)Are the concentrations of heavy metals high enough to be considered as toxic?and(3)Are heavy metals present in mine waste sediments potential sources of pollution?We hypothesized that the physicochemical characteristics of mine waste sediments are less favorably for plant establishment and growth while the concentrations of heavy metals are very high,thus restricting the success of revegetation of mine waste lands.Mine waste sediments were sampled following a diagonal transect across tailings dams,overburden dump sites and the local forest soil from the top layer(0-20 cm)using a closed auger.Samples were analyzed for arsenic,barium,lead,cadmium,cobalt,copper,chromium,nickel,vanadium,and zinc as well as for soil physico-chemical properties.The mine waste sediments were dominated by silt whilst the forest soil by sand particles,with significantly high bulk density in the former.Both the forest soil and overburden sediments were acidic than the alkaline tailings dam sediment.Total organic carbon and nitrogen contents were significantly low in mine wasteland substrates but the concentration of Ca and Mg were significantly higher in tailings dam substrate than the forest soil.The concentrations of available P,K and Na were similar across sites.The mean concentrations of heavy metals were significantly(p<0.01)higher in mine waste sediments than the forest soil;except for cadmium(p=0.213).The order of contamination by heavy metals on the tailings was Cu>Co>Ba>Ni>As>Zn>Pb>Cr>V>Cd,and that on the overburdens was Cu>Co>Ba>Ni>Zn>Cr>Pb>V>As>Cd.The pollution load index(PLI)was nearly twice higher for the tailings dam(8.97)than the overburden(5.84).The findings show that the copper mine wastes(the tailings dams and overburden waste rock sites)are highly contaminated by heavy metals;which,in turn,might pose serious hazards to human health and agricultural productivity.In addition,poor macro-nutrient availability,substrate compaction and soil acidity(particularly on overburden sites)coupled with toxic level of heavy metals would be the main challenges for successful phytostabilization of copper mine wastelands.

A comparative assessment of rock mass deformation modulus

Deformation modulus of a rock mass(E_m) is one of the most important design parameters in construction of rock engineering projects such as underground excavations.However,difficulties are frequently encountered during in-situ tests which are also time-consuming and expensive for determining this parameter.Although E_m is often estimated indirectly from proposed equations by different researchers,many of these equations cannot be used in case of problematic rock conditions(thinly bedded,highly jointed rock masses,etc.) as high quality core samples are required.This study aims to explore more practical and useful equation for E_m estimation using Rock Quality Designation(RQD) and point load index values.Comparisons were made between available empirical equations and the proposed E_m equation in terms of the estimation capacity.Multiple comparison tests(ANOVA) showed that E_m can be reliably estimated using proposed equation especially at the preliminary stages of projects.

Analysis and assessment of nickel and chromium pollution in soils around Baghejar Chromite Mine of Sabzevar Ophiolite Belt,Northeastern Iran

The key objective of this research was to estimate the Ni and Cr contents of soil around the Baghjar Chromite Mine（BCM）of Sabzevar Ophiolite Belt,Northeastern Iran,and assess the degree of soil pollution using the pollution indices.Soil samples（0-20 cm depth） were collected at various distances from the BCM.In the present research,heavy metals（Cr and Ni） in soil samples were analyzed by atomic absorption spectrometry to detect their concentrations and contour maps were produced to explain the metal spatial distribution.Also,the degree of metal pollution was quantified.The results indicate that the soils in the studied area are contaminated by Cr and Ni.The corresponding concentrations for Cr and Ni are（156.19±24.45） and（321.7±133.27） mg/kg,respectively,which exceed the corresponding maximum allowable concentrations in soils.The different indices demonstrate that soils around chromite mine are significantly contaminated with Cr and Ni,suggesting several times higher levels of toxic metals than normal ranges.The above results revealed that the heavy metal concentrations increase with increasing the distance from the mine and mining pollutants can be transported to long distances from their sources.

Development of a location-weighted landscape contrast index based on the minimum hydrological response unit

The changing patterns of watersheds in a landscape, driven by human activities, play an important role in non-point source pollution processes. This paper aims to improve the location-weighted landscape contrast index using remote sensing and GIS technology to account for the effects of scale and ecological processes. The hydrological response unit(HRU) with a single land use and soil type was used as the smallest unit. The relationship between the landscape index and typical ecological processes was established by describing the influence of the landscape pattern on non-point source pollution. To verify the research method, this paper used the Yanshi River basin as a study area. The results showed that the relative intensity of non-point source pollution in different regions of the watershed and the location-weighted landscape contrast index based on the minimum HRU can qualitatively reflect the risk of regional nutrient loss.

Use of generated artificial road profiles in road roughness evaluation

In the evaluation of road roughness and its effects on vehicles response in terms of ride quality, loads induced on pavement, drivers＇ comfort, etc., it is very common to generate road profles based on the equation provided by ISO 8608 standard, according to which it is possible to group road surface profiles into eight different classes. However, real profiles are significantly different from the artificial ones because of the non-stationary fea- ture of the first ones and the not full capability of the ISO 8608 equation to correctly describe the frequency content of real road profiles. In this paper, the international roughness index, the frequency-weighted vertical acceleration awz according to ISO 2631, and the dynamic load index are applied both on artificial and real profiles, highlighting the different results obtained. The analysis carried out in this work has highlighted some limitation of the ISO 8608 approach in the description of performance and conditions of real pavement profiles. Furthermore, the different sensitivity of the various indices to the fitted power spectral density parameters is shown, which should be taken into account when performing analysis using artificial profiles.

A Model Predictive Scheduling Algorithm inReal-Time Control Systems

Abstract-The ineffective utilization of power resources has attracted much attention in current years. This paper proposes a real-time distributed load scheduling algorithm considering constraints of power supply. Firstly, an objective function is designed based on the constraint, and a base load forecasting model is established when aggregating renewable generation and non-deferrable load into a power system, which aims to transform the problem of deferrable loads scheduling into a distributed optimal control problem. Then, to optimize the objective function, a real-time scheduling algorithm is presented to solve the proposed control problem. At every time step, the purpose is to minimize the variance of differences between power supply and aggregate load, which can thus ensure the effective utilization of power resources. Finally, simulation examples are provided to illustrate the effectiveness of the proposed algorithm.

An Evaluation Performance of Potential Pollution of Arsenic, Chromium and Cadmium in the Road Side Soil of Kirkuk City, Northern Iraq

The present work is to evaluate and investigate the distribution of heavy metals (As, Cr and Cd) and to assess the road side samples contamination using an Index (SEPI), (CPI), (GAI), (CF) and (PLI). From right and left Khasa in Kirkuk city, road soil samples were collected in order to estimate the probable contamination level of heavy metals (Cd), (As) and (Cr) in the study area. The heavy metal concentrations were determined in the way side samples by using (ICP-MS) technique. The 22 samples have collected in August, 2013. The results of average levels of heavy metals revealed Cr, As and Cd recorded the highest concentration of (178.6 ppm, 10.4 ppm and 0.599 ppm) in right Khasa respectively. These heavy metals are recorded the lowest value (165.8, 8.29 and 0.4 ppm) in left Khasa respectively. However, the concentration of Cr and As was higher than the studied worldwide permissible of contaminated soil. The highest (SEPI) for As in right Khasa and Cr in left in Khasa seems therefore to be that this road side soil is the most polluted in the city of Kirkuk classified moderately contamination. The accounted of (CPI) for As, Cd and Cr ranged from 0.82 to 1.30 with average 1.01 and 0.6 to 1.12 with an average 0.78 in right and left Khasa respectively. The highest values in the right Khasa which suggest multi-elements contamination and suggested this area of study area received more heavy metals comes from manmade and industrial activities. The GAI showed a moderate contaminated with Cd in right Khasa of study area, while the other metals are in their uncontaminated level. The CF results has been showed by a considerable contamination metals (As, Cr and Cd) in of right Khasa, but low to moderate contamination in left Khasa. The results of (PLI) revealed a deterioration of site quality in all samples of Kirkuk city. Thus the evaluation methods revealed that the studied areas especially right Khasa impacted with heavy industrial activity, phosphate fertilizer, emission of gasses from automobile manufacture tire abrasion and workshop causing an increasing in metal concentrations towards the right Khasa.

Water and Sediment Quality Assessment of a Multipurpose Reservoir in India

Malampuzha reservoir is a multipurpose reservoir in south India. Seven water samples and four sediment samples were studied for the physico-chemical and bacteriological nature of the Malampuzha reservoir water and sediments. Bacteriological analysis indicated the microbial contamination of the reservoir and the physico-chemical characteristics indicated that the water is non potable directly. Analysis of irrigational water quality by SAR, Kelly＇s ratio and SSP indicates that the reservoir water is suitable for irrigation. Heavy metal pollution of the sediments was evaluated based on Sediment Quality Guidelines （SQG）, Pollution Load Index （PLI） and degree of contamination （Cd） of soil in four stations. Principal Component Analysis （PCA） was done to find out the possible linear combination of the original variables of trace metals. Results of PCA showed that no collinearity existed among the studied metals. However, emphasis on the monitoring of Cu and Ni should be preferred because of its alarmingly higher contamination value.

Alternative Method for Concrete Structures Compressive Strength Estimation with Small-Scale Destruction

To estimate a compressive strength from existing concrete structures by core drilling are usually gathered with a diameter specimen of 100 mm or three times of maximum coarse aggregate size and examined by uniaxial compressive strength （UCS）. It is relatively difficult to gather a large sized core, and a pit place will be limited by main members. To get an alternative solution with smaller specimen, point load test （PLT） has been sele,：ted which is a simple test and widely accepted in rock materials research, but relatively new in concrete. The reliability of PLT is evaluated by extracting a lot of core drilled specimen from ready mixed concrete blocks with maximum coarse aggregate size, G of 20 mm in representative of architectural structures and 40 mm in representative of civil structures on the range of concrete grade from 16 to 50. Compressive strengths were classified into general categories, conversion factors were determined, and scattering characteristics were also investigated. The relationship between point load index （Is） and compressive strength of concrete core specimen （fcc） can be written as linear approximation as fcc = k.Is- C.

Assessment of Heavy Metal Contamination in Sea Bed Sediment of the Bight of Bonny, Southern Atlantic Coast of Nigeria Using Index Model Analysis

The heavy metal contamination status of Bight of Bonny sea bed sediment was investigated. Sediment samples were collected from eleven locations grouped into three stations. The samples were analyzed to determine the heavy metals (Fe, Pb, Ni, Zn, Mn, Co, Cd, Cu, Cr) concentration using atomic absorption spectrophotometer. Index model analyses, such as geo-accumulation index (I-geo), Enrichment factor (EF), and Pollution load index (PLI) were used for pollution assessment of sea bed sediment. The most predominant heavy metals in the upstream sediment were Fe;13.57 ± 1.838 mg/kg, cobalt;7.987 ± 3.550 mg/kg, and Ni;1.020 ± 0.802 mg/kg, midstream sediment were Fe;8.554 ± 3.010 mg/kg, Co;8.520 ± 4.00 mg/kg, and Ni;1.140 ± 0.879 mg/kg, while the downstream sediment result had Fe;11.12 ± 3.825 mg/kg, Co;7.275 ± 1.700 mg/kg, and Cd;1.025 ± 0.159 /kg. The I-geo results indicate that Cu, Mn, Pb, Cr, Fe, Zn, Ni, and Co were in their background concentrations while Cd had I-geo > 3 which implies a moderately or heavily polluted environment. The EF indicates metal enrichment from anthropogenic sources for Co, Ni, Pb, Cd, Cu, and Cr while Fe and Mn predicate biogenic origin. The PLI of the heavy metals in the three sample stations of sea bed sediment was found to be generally low (<1). The Enrichment Factor and geo-accumulation index strongly suggest the Bight of Bonny sea bed sediment contamination by Cd from anthropogenic sources.

Atmospheric environmental capacity and urban atmospheric load in China's Mainland

Daily and annual average atmospheric environmental capacity coefficient(A-value) sequences for China's Mainland are calculated from hourly data recorded at 378 ground stations over 1975–2014. A-values at different recurrence intervals are calculated by fitting the sequences to Pearson type III distribution curves. Based on these A-values and source-sink balance(reference concentration 100 μg m^(-3)), atmospheric environmental capacities at the recurrence intervals are calculated for all of China's Mainland and each provincial administrative region. The climate average atmospheric environmental capacity reference value for the entire mainland is 2.169×10~7 t yr^(-1). An urban atmospheric load index is defined for analyses of the impact of population density on the urban atmospheric environment. Analyses suggest that this index is also useful for differentiating whether air quality changes are attributable to varying meteorological conditions or variations of artificial emission rate.Equations guiding the control of unorganized emission sources are derived for preventing air quality deterioration during urban expansion and population concentration.

A novel power system reconfiguration for a distribution system with minimum load balancing index using bacterial foraging optimization algorithm

In this paper, the objective of minimum load balancing index （LBI） for the 16-bus distribution system is achieved using bacterial foraging optimization algorithm （BFOA）. The feeder reconfiguration problem is formulated as a non-linear optimization problem and the optimal solution is obtained using BFOA. With the proposed reconfiguration method, the radial structure of the distribution system is retained and the burden on the optimization technique is reduced. Test results are presented for the 16-bus sample network, the proposed reconfiguration method has effectively decreased the LBI, and the BFOA technique is efficient in searching for the optimal solution.

Modular handover algorithm for 5G HetNets with comprehensive load index

Most existing handover decision system （HDS） designs are monolithic, resulting in high computational cost and unbalance of overall network. A novel modular handover algorithm with a comprehensive load index for the 5th generation （5G） heterogeneous networks （HetNets） is proposed. In this paper, the handover parameters, serving as the basis for handover, are classified into network＇s quality of service （QoS） module, user preference （UP） module and degree of satisfaction （DS） module according to the new modular HDS design. To optimize switching process, the comprehensive network load index is deduced by using triangle module fusion operator. With respect to the existing handover algorithm, the simulation results indicate that the proposed algorithm can reduce the handover frequency and maintain user satisfaction at a higher level. Meanwhile, due to its block calculation, it can bring about 1.4 s execution time improvement.

Spatial Analysis on Content Distribution of Soil Heavy Metals Copper (Cu) and Cadmium (Cd) in Duanzhou District of Zhaoqing City

This paper used atomic absorption spectrophotometry to determine the content distribution of Cu and Cd in the soil of Duanzhou District,Zhaoqing City.The single factor index method,Nemerow comprehensive index method,pollution load index method,geoaccumulation index method,and potential ecological hazard index method were used to analyze the content and pollution status of Cu and Cd in the soil of Duanzhou District,providing a basis for understanding the pollution status of Cu and Cd in the soil of Zhaoqing City.

Spatial Distribution of Magnetic Properties and Selected Heavy Metals in Calcareous Soils as Affected by Land Use in the Isfahan Region,Central Iran

Anthropogenic activities have caused the accumulation of heavy metals in the soil environment. Pollution of the soils significantly reduces environmental quality and affects human health. In many recent studies, magnetic susceptibility ts have been used for pollution monitoring. The objective of this research was to determine the spatial variability of magnetic properties and selected heavy metals and the effect of land use on their variability in the surface soils of the Isfahan region, Central Iran. A total of 158 composite surface （0-5 cm） samples of calcareous soils were collected from an area of about 700 km2, located along a cross-border transect from Isfahan City to a steel plant, covering urban, industrial, agricultural, and uncultivated land uses. Concentrations of copper （Cu）, zinc （Zn）, lead （Pb）, manganese （Mn）, iron （Fe）, nickel （Ni）, chromium （Cr）, and cobalt （Co） and magnetic parameters, magnetic susceptibility at low frequency （xlf）, natural remanent magnetization （NRM）, saturation isothermal remanent magnetization （SIRM）, and isothermal remanent magnetization at the field of 100 mT （IRM100mT） and the backfield of 100 mT （IRM-100mT）, were measured in all the soil samples. Results showed that magnetic susceptibility in the urban and industrial land topsoils （0-5 cm） samples was significantly higher than that in the agricultural and uncultivated land soils in the study area. Concentrations of Cu, Zn, Pb, Mn, and Fe were positively correlated with magnetic properties （xlf, IRM100mT, SIRM, IRM-100mT, and NRM）, which could be attributed to their inputs from traffic emissions and industrial activities at the study sites. Ni and Cr concentrations showed significant negative correlations with magnetic properties. No significant correlation was found between Co concentration and magnetic parameters. The Tomlinson pollution load index （PLI） showed significant correlation with the magnetic properties （xlf, IRM100mT, SIRM, IRM-100mT, and NRM）. The spatial distribution of the selected heavy metals and xlf in the study area suggested that activities at the urban and industrial land sites caused greater pollution as compared to that at the study sites of other land uses. The concentrations of Cu and Zn seemed to have been affected by anthropogenic sources, whereas Ni, Cr, and Co were mainly controlled by natural sources in the study area. Moreover, the concentrations of soil Pb and Fe in the study area could be affected by both lithologic and anthropogenic sources. The magnetic parameters appeared to be a proxy measure for the degree of heavy metal contamination and could be a potential method for the detection and mapping of contaminated soils.

Spatial distribution and source identification of heavy metal pollution in roadside surface soil:a study of Dhaka Aricha highway,Bangladesh

Introduction:In this study,metal pollution and their sources in surface soils were evaluated by pollution indices and multivariate statistical techniques in association with a geographical information system(GIS).Methods:Surface soil samples were collected in dry season from different locations of Dhaka Aricha highway and analyzed by energy dispersive X-ray fluorescence(EDXRF).Results:Thirteen different metals were found in the tested samples.Pollution indices are determined by enrichment factor in an order of Zr>Sn>P>Mn>Zn>Rb>Fe>Ba>Sr>Ti>K>Ca>Al.The resulting geoaccumulation index(Igeo)value shows the following order:Sn>Zr>P>Mn>Zn>Rb>Fe>Ba>Ti>Sr>K>Ca>Al.Contamination factors(CFs)of the metals range from 1.422 to 3.979(Fe);0.213 to 1.089(Al);0.489 to 3.484(Ca);1.496 to 2.372(K);1.287 to 3.870(Ti);2.200 to 14.588(Mn);5.938 to 56.750(Zr);0.980 to 3.500(Sr);2.321 to 4.857(Rb);2.737 to 6.526(Zn);16.667 to 27.333(Sn);3.157 to 16.286(P);and 0.741 to 3.328(Ba).Pollution load index calculated from the CFs indicates that soils are strongly contaminated by Zr and Sn.Principal component analysis(PCA)of parameters exhibits three major components.R-mode cluster analysis reveals three distinct groups in both site and metal basis clustering that shows a similar pattern with the PCA.Conclusions:These results might be helpful for future monitoring of further increase of heavy metal concentrations in surface soils along highways.

Vulnerability of groundwater resources under climate change in the Pannonian basin

The impact of climate change on groundwater vulnerability has been assessed in the Pannonian basin over 1961–2070.High-resolution climatemodels,aquifers composition,land cover,and digital elevation model were the main factors which served to perform the spatial analysis using Geographical Information Systems.The analysis reported here is focused on the long-term period,including three temporal time sets:the past period of 1961–1990(1990s),the present period of 2011–2040(2020s),and the future period of 2041–2070(2050s).During the 1990s,the high and very high areas of groundwater vulnerability were identified in all the central,western,eastern,southeastern,and northern sides of the Pannonian basin.In these areas,the water availability is lower and the pollution load index is high,due to the agricultural activities.The low and very low vulnerability classwas depicted in the South-West part of the basin and in few locations from the peripheral areas,mainly in the North and West.The medium groundwater vulnerability spreads over the Pannonian basin,but it ismore concentrated in the central,South,and South-West.The most affected territory is Hungary,while the territories of Slovenia,Croatia,and Bosnia and Herzegovina are less affected.In the present and future periods,the very high groundwater vulnerability increased in areas by 0.74%and 0.87%,respectively.The low class area decreased between the 1990s and the 2020s by 2.33%and it is expected to decrease up to 2.97%in the 2050s.Based on this analysis and the groundwater vulnerabilitymaps,the Pannonian basin appears more vulnerable to climate change in the present and future.These findings demonstrate that the aquifers from Pannonian basin experience high negative effect under climate conditions.In addition,the land cover contributes to this negative status of groundwater resources.The original maps of groundwater vulnerability represent an instrument for water management planning and for research.