Heat transfer enhanced inorganic phase change material compositing carbon nanotubes for battery thermal management and thermal runaway propagation mitigation

Developing technologies that can be applied simultaneously in battery thermal management(BTM)and thermal runaway(TR)mitigation is significant to improving the safety of lithium-ion battery systems.Inorganic phase change material(PCM)with nonflammability has the potential to achieve this dual function.This study proposed an encapsulated inorganic phase change material(EPCM)with a heat transfer enhancement for battery systems,where Na_(2)HPO_(4)·12H_(2)O was used as the core PCM encapsulated by silica and the additive of carbon nanotube(CNT)was applied to enhance the thermal conductivity.The microstructure and thermal properties of the EPCM/CNT were analyzed by a series of characterization tests.Two different incorporating methods of CNT were compared and the proper CNT adding amount was also studied.After preparation,the battery thermal management performance and TR propagation mitigation effects of EPCM/CNT were further investigated on the battery modules.The experimental results of thermal management tests showed that EPCM/CNT not only slowed down the temperature rising of the module but also improved the temperature uniformity during normal operation.The peak battery temperature decreased from 76℃to 61.2℃at 2 C discharge rate and the temperature difference was controlled below 3℃.Moreover,the results of TR propagation tests demonstrated that nonflammable EPCM/CNT with good heat absorption could work as a TR barrier,which exhibited effective mitigation on TR and TR propagation.The trigger time of three cells was successfully delayed by 129,474 and 551 s,respectively and the propagation intervals were greatly extended as well.

Low Carbon Building Design Optimization Based on Intelligent Energy Management System

The construction of relevant standards for building carbon emission assessment in China has just started,and the quantitative analysis method and evaluation system are still imperfect,which hinders the development of low-carbon building design.Therefore,the use of intelligent energy management system is very necessary.The purpose of this paper is to explore the design optimization of low-carbon buildings based on intelligent energy management systems.Based on the proposed quantitative method of building carbon emission,this paper establishes the quota theoretical system of building carbon emission analysis,and develops the quota based carbon emission calculation software.Smart energy management system is a low-carbon energy-saving system based on the reference of large-scale building energy-saving system and combined with energy consumption.It provides a fast and effective calculation tool for the quantitative evaluation of carbon emission of construction projects,so as to realize the carbon emission control and optimization in the early stage of architectural design and construction.On this basis,the evaluation,analysis and calculation method of building structure based on carbon reduction target is proposed,combined with the carbon emission quota management standard proposed in this paper.Taking small high-rise residential buildings as an example,this paper compares and analyzes different building structural systems from the perspectives of structural performance,economy and carbon emission level.It provides a reference for the design and evaluation of low-carbon building structures.The smart energy management system collects user energy use parameters.It uses time period and time sequence to obtain a large amount of data for analysis and integration,which provides users with intuitive energy consumption data.Compared with the traditional architectural design method,the industrialized construction method can save 589.22 megajoules(MJ)per square meter.Based on 29270 megajoules(MJ)per ton of standard coal,the construction area of the case is about 8000 m2,and the energy saving of residential buildings is 161.04 tons of standard coal.This research is of great significance in reducing the carbon emission intensity of buildings.

Cultivation and Management of Low-carbon Scenic Spots——A case study of Yuntai Mountain Scenic Area in Henan Provicne of China

After analysis of connotation of low-carbon scenic spots,the paper considered that a perfect low-carbon scenic spot is a comprehensive integrity with satisfying tourists' lowest tourist experience effect as the premise and with low energy consumption,low pollution and low emission as the foundation.Low-carbon tourist scenic spots had been classified into three types which are ecological type,cultural type and coupling type of ecology and culture.Representatives of each type of tourist scenic spot were illustrated.It proposed that government should play the leading role in cultivation of low-carbon scenic spot;tourism industry should enhance self supervision;tourism development mode should be transformed and upgrading of tourist products should be realized.By taking Yuntai Mountain Scenic Area of Henan Province for example,based on low-carbon tourist resources,low-carbon development of management,following measures realizing low-carbon economy were put forward:① purifying air quality and beautifying environment of scenic area;② sifting laggard productivity and protecting ecological resources in the scenic area by many means;③ sticking to low-carbon environmental protection concept and completing infrastructure service;④ developing tourist native products and souvenirs based on local resources;⑤ applying electronic access control ticket system,intelligent monitor system and LED information and communication platform,so as to achieve low-carbon management.

"Three-in-One" Multi-Scale Structural Design of Carbon Fiber-Based Composites for Personal Electromagnetic Protection and Thermal Management

Wearable devices with efficient thermal management and electromagnetic interference(EMI) shielding are highly desirable for improving human comfort and safety. Herein, a multifunctional wearable carbon fibers(CF) @ polyaniline(PANI)/silver nanowires(Ag NWs) composites with a “branch-trunk” interlocked micro/nanostructure were achieved through "three-in-one" multi-scale design. The reasonable assembly of the three kinds of one-dimensional(1D) materials can fully exert their excellent properties i.e., the superior flexibility of CF, the robustness of PANI, and the splendid conductivity of Ag NWs. Consequently, the constructed flexible composite demonstrates enhanced mechanical properties with a tensile stress of 1.2 MPa, which was almost 6 times that of the original material. This is mainly attributed to the fact that the PNAI(branch) was firmly attached to the CF(trunk) through polydopamine(PDA), forming a robust interlocked structure. Meanwhile, the composite possesses excellent thermal insulation and heat preservation capacity owing to the synergistically low thermal conductivity and emissivity. More importantly, the conductive path of the composite established by the three 1D materials greatly improved its EMI shielding property and Joule heating performance at low applied voltage. This work paves the way for rational utilization of the intrinsic properties of 1D materials, as well as provides a promising strategy for designing wearable electromagnetic protection and thermal energy management devices.

Properties of Activated Carbons from Sugarcane Leaves and Rice Straw Derived Charcoals by Activation at Low Temperature via KMnO_(4)Pre-Oxidation-Hydrolysis

Activated carbon preparation from sugarcane leaves and rice straw by carbonization(250℃–400℃)and activation at 500℃were studied.The effects of pre-oxidation,hydrolysis of derived charcoals by boiled KMnO4 aqueous solution were evaluated.The derived charcoals products were pretreated using oxidation-hydrolysis with 1–5 wt.%KMnO4 at 100℃and then activated at 500℃.The derived charcoal and activated carbon products were characterized by FTIR,XRD,SEM-EDS and BET.Iodine number and methylene blue number of derived products were also used for the analysis of the products.It was found that fabricated charcoal materials made at 350℃–400℃possess good characteristics with low content of surface functional groups and high carbon content.After pre-oxidation-hydrolysis and activation at 500℃,the resulting derived activated carbon materials from charcoals with 400℃carbonization temperature have high content of oxygen containing surface functional groups such as Mn-O,Si-O,Si-O-Si,C-O,or O-H.In addition,MnO_(2) accumulated on the surface of the derived activated carbon products.The surface area and pore volume of the activated carbon products have also increased with increasing of KMnO_(4) concentration from 1 to 3 wt.%and then decreased with 5 wt.%used during activation.Therefore,activated carbon products made by pre-oxidation-hydrolysis with 3 wt.%KMnO_(4) were used for Fe(Ⅲ)adsorption experiments.It was found that Fe(Ⅲ)adsorption on the activated carbon materials can be fitted with both the Freundlich and the Langmuir models.The calculated maximum Fe(Ⅲ)adsorption capacities of sugarcane leaves derived activated carbon and rice straw derived activated carbon products were 50.00 and 39.37 mg/g,respectively.It was shown that the effect of pre-oxidation-hydrolysis by KMnO_(4) and activation at 500℃are beneficial for activated carbon preparation with environmentally friendly and low-cost simplified operation.

Collaborative robust dispatch of electricity and carbon under carbon allowance trading market

The launch of the carbon-allowance trading market has changed the cost structure of the power industry.There is an asynchronous coupling mechanism between the carbon-allowance-trading market and the day-ahead power-system dispatch.In this study,a data-driven model of the uncertainty in the annual carbon price was created.Subsequently,a collaborative,robust dispatch model was constructed considering the annual uncertainty of the carbon price and the daily uncertainty of renewable-energy generation.The model is solved using the column-and-constraint generation algorithm.An operation and cost model of a carbon-capture power plant(CCPP)that couples the carbon market and the economic operation of the power system is also established.The critical,profitable conditions for the economic operation of the CCPP were derived.Case studies demonstrated that the proposed low-carbon,robust dispatch model reduced carbon emissions by 2.67%compared with the traditional,economic,dispatch method.The total fuel cost of generation decreases with decreasing,conservative,carbon-price-uncertainty levels,while total carbon emissions continue to increase.When the carbon-quota coefficient decreases,the system dispatch tends to increase low-carbon unit output.This study can provide important guidance for carbon-market design and the low-carbon-dispatch selection strategies.

Ecosystem service multifunctionality of mixed conifer-broad-leaved forests under climate change and forest management based on matrix growth modelling

Climate change and forest management are recognized as pivotal factors influencing forest ecosystem services and thus multifunctionality.However,the magnitude and the relative importance of climate change and forest management effects on the multifunctionality remain unclear,especially for natural mixed forests.In this study,our objective is to address this gap by utilizing simulations of climate-sensitive transition matrix growth models based on national forest inventory plot data.We evaluated the effects of seven management scenarios(combinations of various cutting methods and intensities)on the future provision of ecosystem services and multifunctionality in mixed conifer-broad-leaved forests in northeastern China,under four climate scenarios(SSP1-2.6,SSP2-4.5,SSP5-8.5,and constant climate).Provisioning,regulating,cultural,and supporting services were described by timber production,carbon storage,carbon sequestration,tree species diversity,deadwood volume,and the number of large living trees.Our findings indicated that timber production was significantly influenced by management scenarios,while tree species diversity,deadwood volume,and large living trees were impacted by both climate and management separately.Carbon storage and sequestration were notably influenced by both management and the interaction of climate and management.These findings emphasized the profound impact of forest management on ecosystem services,outweighing that of climate scenarios alone.We found no single management scenario maximized all six ecosystem service indicators.The upper story thinning by 5%intensity with 5-year interval(UST5)management strategy emerged with the highest multifunctionality,surpassing the lowest values by more than 20%across all climate scenarios.In conclusion,our results underlined the potential of climate-sensitive transition matrix growth models as a decision support tool and provided recommendations for long-term strategies for multifunctional forest management under future climate change context.Ecosystem services and multifunctionality of forests could be enhanced by implementing appropriate management measures amidst a changing climate.

Forest management causes soil carbon loss by reducing particulate organic carbon in Guangxi, Southern China

Background: The loss of soil organic carbon(SOC) following conversion of natural forests to managed plantations has been widely reported. However, how different SOC fractions and microbial necromass C(MNC) respond to forest management practices remains unclear.Methods: We sampled 0–10 cm mineral soil from three different management plantations and one protected forest in Guangxi, Southern China, to explore how forest management practices affect SOC through changing mineralassociated C(MAOC) and particulate organic C(POC), as well as fungal and bacterial necromass C.Results: Compared with the protected forest, SOC and POC in the abandoned, mixed and Eucalyptus plantations significantly decreased, but MAOC showed no significant change, indicating that the loss of SOC was mainly from decreased POC under forest management. Forest management also significantly reduced root biomass, soil extractable organic C, MNC, and total microbial biomass(measured by phospholipid fatty acid), but increased fungi-to-bacteria ratio(F:B) and soil peroxidase activity. Moreover, POC was positively correlated with root biomass, total microbial biomass and MNC, and negatively with F:B and peroxidase activity. These results suggested that root input and microbial properties together regulated soil POC dynamics during forest management.Conclusion: Overall, this study indicates that forest management intervention significantly decreases SOC by reducing POC in Guangxi, Southern China, and suggests that forest protection can help to sequester more soil C in forest ecosystems.

Research and Experience Reference on China’s Implementation of Low Carbon Strategy

Economic development has brought about global greenhouse gas emissions, which in turn has brought about global climate change. This research paper aims to compare the strengths and weaknesses that China has demonstrated in the implementation of its low-carbon city strategy and to summarise the valuable experience that China can provide to the world in the implementation of its low-carbon city strategy. This essay analyses in depth the advantages that China has shown in the areas of renewable energy use and government mechanisms, as well as the shortcomings that it has shown in the areas of eco-efficiency industrial structure and capacity upgrading. Then, the paper summarises the successful experiences of the Chinese government in the establishment of renewable energy use and governmental mechanisms, such as the local government’s ability to coordinate multiple sectors (industrial sector, energy sector, etc.) and the implementation of responsibilities. In comparison, the paper also further discusses that China’s implementation of a low-carbon strategy in the future may have more eco-efficiency, industrial structure and capacity upgrading.

Properties and Characterization of Two Clays Raw Material from Mountain District (West of Côte d’Ivoire) for Use in Low-Carbon Cements

This work was devoted to the study of the physico-chemical properties of two clay minerals from the Mountain District (West Côte d'Ivoire) referenced ME1 and ME2. These samples were characterized by the experimental techniques, such as X-ray diffraction (XRD), Infrared spectroscopy (IR), Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), Differential Thermal Analysis and Thermogravimetry (DTA-TG), Brunauer, Emett and Teller method (BET), laser particle size analysis and Scanning Electron Microscope (SEM). The main results of these analyses reveal that the two clay samples mainly contain quartz (52.91% for ME1 and 51.72% for ME2), kaolinite (36.60% for ME1 and 41.6% for ME2) and associated phases, namely goethite and hematite (13.47% for ME1 and 11.00% for ME2). The specific surface values obtained for samples ME1 and ME2 are 34.78 m2/g and 29.18 m2/g respectively. The results obtained show that the samples studied belong to the kaolinite family. After calcination, they could have good pozzolanic activity and therefore be used in the manufacture of low-carbon cements.

Cassava Groundnut Intercropping: A Sustainable Land Management Practice for Increasing Crop Productivity and Organic Carbon Stock on Smallholder Farms

Cassava-groundnut intercropping is not a common practice among smallholder farmers in Sierra Leone even though both crops are well suited for intercropping. On-farm trials were conducted in three locations (Bai Largor, Bassah, and Njala Kanima) in the Moyamba district during the 2021 cropping season to investigate the efficacy of cassava-groundnut intercropping for increasing crop productivity and soil organic carbon stock on smallholder farms in the Moyamba district, Southern Sierra Leone. The experimental design was a randomized complete block design in three replications with treatments of sole groundnut, sole cassava and cassava-groundnut intercropping. Data on the yield and yield components of cassava and groundnut were analysed using the PROC MIXED procedure of SAS 9.4 and means were compared using the standard error of difference (SED). The above-ground biomass, number of roots per plant, and fresh root yield of cassava were not significantly (p > 0.05) affected by the cassava-based cropping system. Averaged across locations, intercropping cassava with groundnut decreased the above-ground biomass, the number of roots per plant, and fresh root yield of cassava by 17%, 11%, and 17%, respectively. The above-ground biomass, number of pods per plant and fresh pod yield of groundnut were significantly (p 1), the highest net revenue and benefit-cost ratio. The benefit-cost ratio was also favourable for the sole cassava (BCR > 1) but not favourable for the sole groundnut (BCR < 1). Averaged across locations, intercropping cassava with groundnut increased the benefit-cost ratio by 121% and 13% when compared to the sole groundnut and sole cassava. In the event of a 40% yield loss for the cassava and groundnut, the benefit-cost ratio was favourable (1.12) only for the cassava groundnut intercropping system. The net soil organic carbon stock was favourable only for the cassava-groundnut intercrop. Averaged across locations, the net soil organic carbon for the cassava-groundnut intercropping increased by 3.4% when compared to the baseline within one cropping cycle of the cassava (12 months). The results confirm that cassava-groundnut intercropping is a sustainable land management practice that could enhance crop productivity and soil organic carbon stock on smallholder farms.

Soil Carbon Pool Management Index under Different Straw Retention Regimes

[Objective] To clarify the effects of different straw retention regimes on soil fertility in double cropping paddy field. [Method] The effects of different straw reten- tion regimes on total organic carbon （CToc）, active carbon （CA） and mineralized carbon （CM） were analyzed, and carbon pool active （A）, carbon pool active index （A/）, carbon pool index （CPI） and carbon pool management index （CPMi） for each treat- ment were calculated. [Result] Compared with the unfertilized treatment （CK）, CToc, CA, CM and the available ratio of soil carbon were increased in the treatment of re- turning early season and late season rice straws to field. With the same nutrient application, CToc, CA and the available ratio of soil carbon in the field with straw re- turned to field were higher than that of straw incineration and no straw returning, and the change in soil CA content was more significant. The difference in CPMI be- tween different treatments reached significant or very significant level, and the value was in the order of straw directly returned to field 〉 straw returned to field after in- cineration 〉 no straw returned to field. [Conclusion] This study provided theoretical bases for the increase of soil CA content and soil fertility in double rice fields.

Management Strategies and Their Evaluation for Carbon Sequestration in Cropland

In order to deal with the global change and to reduce emission of greenhouse gas, a number of countries have strengthened studies on carbon sequestration in cropland. Carbon sequestration in cropland is not only an important component for the global carbon stock, but also is the most active part to sequestrate the carbon in soil from atmosphere. In this sense, it is of necessity and significance to strengthen the study on management of carbon sequestration in cropland. Based on the main factors affecting carbon cycle in agro-ecosystems, this paper summarizes the relevant management measures to strengthen the capacity of reducing emission of carbon and increasing the carbon sequestration in cropland, and evaluates the effects of these measures after being implemented at a regional extent.

Effects of Different Land Use Types on Soil Organic Carbon and Carbon Management Index in Karst Area

[Objective] The aim was to reveal changes of soil organic matter fraction and their corresponding carbon management indexes as affected by different land use types.[Method]Soil organic carbon,active soil organic carbon and soil carbon management index（CMI）of different land use types in Guilin Maocun karst area were studied.Sampling with field investigation and laboratory testing was carried out.Heavy potassium chromate method was adopted to determine soil organic matter.333 mmol/L KMnO4 oxidation method was used to determine active organic carbon.[Result]With active soil organic matter increasing,the differences of CMI between different land use types were bigger.The CMI value of different land uses was shrubforest paddy fielddry farmland.The statistical analysis showed that labile organic matter was related with major soil properties at a significant level.[Conclusion]Labile organic matter could be used to reveal the influence of different land use types on soil organic matter and carbon management index in karst area.

Eff ects of thinning on ecosystem carbon storage and tree-shrub-herb diversity of a low-quality secondary forest in NE China

Thinning is a widely used forest management tool but systematic research has not been carried out to verify its eff ects on carbon storage and plant diversity at the ecosystem level.In this study,the eff ect of thinning was assessed across seven thinning intensities(0,10,15,20,25,30 and 35%)in a low-quality secondary forest in NE China over a ten-year period.Thinning aff ected the carbon storage of trees,and shrub,herb,and soil layers(P<0.05).It fi rst increased and then decreased as thinning intensity increased,reaching its maximum at 30%thinning.Carbon storage of the soil accounted for more than 64%of the total carbon stored in the ecosystem.It was highest in the upper 20-cm soil layer.Thinning increased tree species diversity while decreasing shrub and herb diversities(P<0.05).Redundancy analysis and a correlation heat map showed that carbon storage of tree and shrub layers was positively correlated with tree diversity but negatively with herb diversity,indicating that the increase in tree diversity increased the carbon storage of natural forest ecosystems.Although thinning decreased shrub and herb diversities,it increased the carbon storage of the overall ecosystem and tree species diversity of secondary forest.Maximum carbon storage and the highest tree diversity were observed at a thinning intensity of 30%.This study provides evidence for the ecological management of natural and secondary forests and improvement of ecosystem carbon sinks and biodiversity.

Rural Carbon Emissions Based on Community Management

Rural community is an effective way to simultaneously achieve manage- ment of ecological resources and protection of natural resources, depending on its management mode based on cooperation, motivation, local experiences and extensi- ble boundary. In the research, carbon emission in community is a kind of ecological resources and negative externality is the cause of increase of rural carbon emission. Compared with governmental ruling and marketing approach, community manage- ment mode proves more effective to solve the problem of negative externality of carbon emission in community. Furthermore, rural carbon, emission was analyzed in detail on basis of community management mode and extending mode of carbon emis- sion in rural areas. In addition, some policies and suggestions were proposed to im- prove community management of carbon emission in rural areas, providing an ef- fective way for low-carbon economy in rural areas.

Policy and Management of Carbon Peaking and Carbon Neutrality:A Literature Review

The vision of reaching a carbon peak and achieving carbon neutrality is guiding the low-carbon transition of China’s socioeconomic system.Currently,a research gap remains in the existing literature in terms of studies that systematically identify opportunities to achieve carbon neutrality.To address this gap,this study comprehensively collates and investigates 1105 published research studies regarding carbon peaking and carbon neutrality.In doing so,the principles of development in this area are quantitively analyzed from a space–time perspective.At the same time,this study traces shifts and alterations in research hotspots.This systematic review summarizes the priorities and standpoints of key industries on carbon peaking and carbon neutrality.Furthermore,with an emphasis on five key management science topics,the scientific concerns and strategic demands for these two carbon emission-reduction goals are clarified.The paper ends with theoretical insights on and practical countermeasures for actions,priority tasks,and policy measures that will enable China to achieve a carbon-neutral future.This study provides a complete picture of the research status on carbon peaking and carbon neutrality,as well as the research directions worth investigating in this field,which are crucial to the formulation of carbon peak and carbon neutrality policies.

Effect of Management Practices on Seasonal Dynamics of Organic Carbon in Soils Under Bamboo Plantations

Soil samples for conventional management (CM) and intensive management (IM) practices were taken over a year at 2-month intervals to determine the effect of management practices on soil organic carbon (SOC) and to quantify seasonal dynamics in SOC for bamboo (Phyllostachys pubescens Mazel ex H. de Lehaie) stands. The results with IM compared to CM showed large decreases in total organic carbon (TOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC), and the MBC/TOC ratio in the soils. With all IM plots in the 0-20 cm depth across sampling periods, average decreases compared with CM were: TOC, 12.1%; MBC, 26.1%; WSOC, 29.3%; the MBC/TOC ratio, 16.1%; and the WSOC/TOC ratio, 20.0%. Due to seasonal changes of climate, seasonal variations were observed in MBC and WSOC. Soil MBC in the 0-20 cm depth in September compared to May were 122.9% greater for CM and 57.6% greater for IM. However, due primarily to soil temperature, soil MBC was higher during the July to November period, whereas because of soil moisture, WSOC was lower in July and January. This study revealed that intensive management in bamboo plantations depleted the soil C pool; therefore, soil quality with IM should be improved through application of organic manures.

Forest management required for consistent carbon sink in China’s forest plantations

Background:Forest is the largest biomass carbon(C)pool in China,taking up a substantial amount of atmospheric carbon dioxide.Although it is well understood that planted forests(PFs)act as a large C sink,the contribution of human management to C storage enhancement remains obscure.Moreover,existing projections of forest C dynamics suffer from spatially inconsistent age and type information or neglected human management impacts.In this study,using developed PF age and type maps and data collected from 1371 forest plantation sites in China,we simulated biomass C stock change and quantified management impacts for the time period 2010-2050.Results:Results show that future forest biomass C increment might have been overestimated by 32.5%-107.5% in former studies.We also found that age-related growth will be by far the largest contributor to PF biomass C increment from 2010 to 2050(1.23±0.002 Pg C,1 Pg=10^(15) g=1 billion metric tons),followed by the impact of human management(0.57±0.02 Pg C),while the contribution of climate is slight(0.087±0.04 Pg C).Besides,an additional 0.24±0.07 Pg C can be stored if current PFs are all managed by 2050,resulting in a total increase of 2.13±0.05 Pg C.Conclusions:Forest management and age-related growth dominate the biomass C change in PFs,while the effect of climatic factors on the accumulation is minor.To achieve the ambitious goal of forest C stock enhancement by 3.5 Pg from 2020 to 2050,we advocate to improve the management of existing forests and reduce the requests for more lands for forest expansion,which helps mitigate potential conflicts with agricultural sectors.Our results highlight that appropriate planning and management are required for sustaining and enhancing biomass C sequestration in China’s PF.

Analysis and management strategies for the low voltage problems of rural power grid based on the distribution network flow calculation method

For a long time, because of the lack of investment capital and enough attentions, the overall constructions of rural power grid were far behind than the urban power grid in Chongqing Jiangbei Power Company. The low voltage problems were highlighted in the rural power grid due to the characteristics of rural power grid. Using the distribution network flow calculation method, we evaluated the low voltage problems of the rural power grid which belongs to Chongqing Jiangbei Power Company. In addition, we collected the data of distribution transformers in electricity consumption peak period. Some practical management strategies were proposed by the analysis and evaluation of potential and appeared low voltage problems.