Archive

  • Select all
    |
    Orginal Article
  • Orginal Article
    GAO Yang,ZHANG Fengrong,HAO Jinmin,ZHANG Bailin,ZHOU Jian
    Download PDF ( ) HTML ( )   Knowledge map   Save

    As an effective measure,rural residential land consolidation can not only intensify rural residential land use,but also relieve contradictions between urban and rural land use. Consolidation potential calculation and urgency degree evaluation are the basis of rural residential land consolidation sequencing. Here,we used geological data and economic social materials obtained from GIS spatial techniques,global observation and interviews in Wuxiang County,Shanxi,China to obtain land structure inside rural residential land. Depending on land type and property,we classified consolidation potential into two types:shallow potential and deep potential. Our results show that the proportion of shallow potential is 71.88%,implying that shallow potential is the main component of total potential. We chose sixteen factors from nature and four aspects from socio-economy and infrastructure,and used them to evaluate the consolidation urgency degree of rural settlements. According to urgency degree evaluation scores we divided 106 sample villages into four classes:most urgent villages,more urgent villages,urgent villages and not urgent villages. We then chose the most urgent and more urgent villages as counties to be consolidated and classified them into eight combination types with percentages of shallow potential in total potential and total potential in the rural settlement area. Last,we arranged the order of eight combination counties into three time quanta and found that there are 13 villages to be consolidated in the near future,17 villages in the mid-term and 19 longer-term.

  • Orginal Article
    XU Anqi,GAO Xuesong,LI Qiquan,XIE Ting
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Research into village hollowing in the Chengdu Plain, China has become important and urgent because of the need for the sustainable utilization of land resources. Here, we collected socio-economic data from statistical yearbooks, field investigations and household interviews, and obtainedaerial photographs from private unmanned aerial vehicles. We developed a type identification system for village hollowing from three dimensions: hollowing degree, aggregation degree and driving force. Hollowing degree was defined as the ratio of disused homestead area; aggregation degree was calculated using the Average Nearest Neighbor Distance; and driving force was decidedusing a combined approach of analytic hierarchy and entropy methods. Characteristic analysis and type identification were then conducted to classify five sample villages into five categories such as ‘outer-driving village hollowing with high hollowing degree and scattered settlement distribution’. We found that the hollowing degree of Qinjiamiao, Zhongping and Yongsheng are above 7.15%, indicating that they are at a high level of hollow degree, while that of Yonghe and Yongsheng are below 7.15%, indicating a low hollowing degree.Disused homesteads in the five sample villages are scattered, with nearest neighbor distance indices greater than 1. Driving forces in Qinjiamiao and Yongsheng belong to the outer-driving type, indicating that village hollowing in these areas is deeply shaped by urbanization and industrialization. Yonghe and Xianfeng belong to the inner-driving type, where village hollowing is mainly the consequence of residential condition decline. Zhongping belongs to the outer-inner-driving type, displaying features of two other driving types.

  • Orginal Article
    WANG Xiaoyu,HU Shougeng,TONG Luyi
    Download PDF ( ) HTML ( )   Knowledge map   Save

    With continued advances of ‘four modernizations’ construction and urban-rural development strategies,rapid growth in the demand for construction land is threatening cultivated land resources. However,comprehensive cognition of the characteristics and distribution of cultivated land resource values is an important prerequisite when promoting urban-rural land market construction,and it can also provide decision support for coordinating rural and urban development. On the basis of combing current cultivated land resource value connotation,here we built an evaluation system of prefecture cultivated land resource value,and using Tuanfeng county in Hubei,China as an example we measured the economic,social and ecological value of prefectural cultivated land resources and analyzed the spatial distribution at village,town and county regional scales. We found that the proportion of cultivated land resource ecological,social and economic value is approximately 532,and the comprehensive value is up to 466.85 CNY/m2,which is 8.8 times over current land expropriation compensation standards. The southern prefectural cultivated land resource economy and ecological value is higher than in the north,mainly because of topographic conditions. There is an obvious agglomeration effect in cultivated land resource values in local parts. The comprehensive value is closely related to location and traffic conditions of cultivated land, and there is a "low-value" agglomeration effect around the region of Dupi and Jiamiao Town. These data provide scientific support and an effective reference for local decision-making departments to identify factors that affect cultivated land resources value,reveal the formation mechanism of cultivated land price,and facilitate the construction of urban-rural integral land markets.

  • Orginal Article
    ZHAO Aidong,MA XianLei,QU Futian,XU Shi
    Download PDF ( ) HTML ( )   Knowledge map   Save

    To optimize the allocation of land resources, China should speed up the industrial land market reform, and measure the industrial land marketization level is significance for the evaluation of the performance of industrial land market reform. Based on industrial land leasing data for 238 prefecture-level cities in China from 2007 to 2013,we investigated temporal-spatial evolution patterns of industrial land marketization in China from the dimensions of industrial land leasing premium rate and leasing mode marketization to analyze factors impacting regional differences. The results show that China's the industrial land marketization level rose from 7.66 in 2007 to 32.16 in 2013;industrial land leasing price in China has not yet reflected the value of industrial land revealed by resource scarcity and market conditions. Land market reform remains at a stage of simply changing leasing mode and not deeping into the core that establishes industrial land pricing mechanisms,reflecting the extent of resource scarcity. Industrial land marketization is continuously deepening in eastern,central and western China. The eastern marketization level is not only the highest level but also the fastest;central and western industrial land market reform remains in a transition from passive compliance with central government regulations to initiatives that direct industrial land market reform endogenously. Meanwhile,the level of economic development,industrial structure and industrial land demand intensity showed significant positive relationships with industrial land marketization. Land resource endowments had a significant negative effect,while regional fierce competition for business inhibits the industrial land market reform process in China. It is suggested that perfecting the land grant system and establishing market ecology should be an important position in the process of industrial land market reform,promoting industrial land prices to a reasonable value and optimizing the allocation of resources.

  • Orginal Article
    PENG Shangui,WANG Yinghong,CHEN Chen,WANG Jian,LEI Gang,WU Xianhua
    Download PDF ( ) HTML ( )   Knowledge map   Save

    This paper investigated the scale of industrial land from the view of local government behavior in land supply and adopted panel data for all cities in Shandong, China from 2001 to 2012. We used threshold regression modeling to analyze the reasonable scale of industrial land for all cities in Shandong and studied the classification and research of driving forces of rational and irrational industrial land. The results reveal that according to the different ways of per land area industrial capital stock on industrial economic output, the scale of industrial land can be divided into rational and irrational types. There is a positive effect on industrial economy while per land area industrial capital stock is greater than 40.791 billion/km2 in Shandong, and it can be called a reasonable scale while the scale of industrial land is in this interval; otherwise it is known as an unreasonable scale. From 2001 to 2012, the scale of irrational industrial land of Shandong decreased from 212.03 km2 to 100.74 km2, while irrational industrial land accounts for the proportion of the total amount of industrial land that decreased from 46.49% to 9.19%; the scale of irrational industrial land was mainly concentrated in western and southern Shandong province. Rational industrial land expansion mainly was the result of economic and demographic factors, while irrational industrial land expansion was mainly driven by institutional factors such as tax system and performance evaluation system of local officials, and other systems. Regulation and control of industrial land expansion should ensure land-capital allocation relation within a reasonable range, by means of reform in financial and official promotion appraisal system to constrain local government’s irrational land supply behavior and prevent its impact on industrial land expansion.

  • Orginal Article
    HUA Jian,LI Zhenglin,HUANG Dechun
    Download PDF ( ) HTML ( )   Knowledge map   Save

    The global water crisis is growing day by day and cooperation in international river water resource development is more and more important.Here weconsiderinternational river water resource development cooperation asa political, economic, ecological, socialand cultural dissipative and complex system. Based on system environment and behavior and interpretative structural modeling of internal subsystem structures, we point out that the communication coordination subsystem is acore part of the system running effect, and water carrier subsystem is the foundation of system operation.We found that barriers to cooperation include river-related differences, demands of stakeholders, th ecological destruction caused by cooperation and development, information sharing, politicaland military disputes, efficiency of governments and enterprise management.Promoters of effective cooperation include good political situations, human support, financial support, ecological restoration and compensation mechanisms, and an improved international wading regime.Based on increasing and decreasing entropy based on factors affecting index systemdesign, we constructinternational river water cooperation via a system entropy model, discussmeasures under the total entropy of different suggestions, and provide specific guidance for international river water resource cooperation.

  • Orginal Article
    LONG Qiubo,JIA Shaofeng,WANG Dangxian
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Water use statistics are critical to regional water resource planning and management and the basis of strict implementation of water resource management strategies in China. Based on water use data in China water resources bulletins and the first national census for water, disparity in water use data and reasons for these disparities were analyzed using comparison, the Delphi expert survey method and the trend deviation method. Proper water statistics are chosen and modified to objectively determine the true water use situation in China. This study demonstrated that differences in water statistics are objective. Water use data disparities vary among different regions and sectors. The main reasons are weak water metering foundations, low measurement rates and local administrative departmental effects on water data reporting so as to gain equivalent water rights water indicators. The revised total water use of China in 2011 was 590.5 billion m3, of which domestic water consumption was 84.6 billion m3, industrial water consumption was 120.3 billion m3, and agricultural water consumption was 374.4 billion m3.

  • Orginal Article
    GU Mengchen,WANG Limao
    Download PDF ( ) HTML ( )   Knowledge map   Save

    There are differences in CO2 emissions resulting from petroleum terminal utilization consumption among regions in China. This paper investigated a proper method to measure CO2 emissions from petroleum terminal utilization consumption in China using data from 30 provinces. To study carbon emission spatial distribution features we used the Moran’I model and found that the emissions intensity of China's petroleum terminal utilization showed universal positive spatial correlation; specifically,spatial correlation based and partial spatial discontinuity/mutation supplemented. It turns out that northeast and northwest regions were the main areas of high emission intensity,the western region had relatively high emission intensity as a whole,and the mid-eastern region had relatively low emission intensity. Shandong,Henan,Anhui,Jiangsu,Hubei and Jiangxi in eastern and central China were clusters of low CO2 emission intensity,surrounding provinces also showed low CO2 emission intensity. However,Jilin was in the CO2 emission intensity depression,and looking forward,Jilin could serve as a model for surrounding provinces such as Heilongjiang,Liaoning,and Inner Mongolia which mostly have a high CO2 emission intensity. The emission intensity had positive and strong relations with economic development level,energy conditions and industrial structures in these provinces. Therefore,to develop regional carbon emission reduction policy,governments should develop demission policy with regional subdivision and fully consider the practical situation of each province. Governments should also develop an overall plan to coordinate and promote the optimization of industry structure and energy structure.

  • Orginal Article
    ZHANG Miao,GAN Chenlin,CHEN Yinrong,CHEN Lu
    Download PDF ( ) HTML ( )   Knowledge map   Save

    We analyzed the efficiency values of carbon emissions from development intensity of urban construction land and explored low-carbon optimization strategies for development and utilization of urban construction land. Methods of modeling and comparative analyses were used. We found that the development intensity of urban construction land and the efficiency of carbon emissions is a process of dynamic change in time and space, but the changes are inconsistent. The development intensity of construction land in three regions slightly increased from 2003 to 2006 (the intensity of eastern China is the highest), but increased greatly from 2006 to 2009, and the intensity of three regions is insignificant. The three regions were significantly increasing from 2009 to 2012, the intensity of western China is the highest. The spatial distribution of carbon emission efficiency effective values changes from western and central to eastern China and western and eastern regions have the higher carbon emission efficiency values. Lacking technical efficiency is the main reason for low overall efficiency of carbon emissions. Eastern China decreased construction land development intensity to improve efficiency in carbon emissions; central and western China increased construction land development intensity but cannot give consideration to carbon efficiency. We conclude that the development intensity of urban construction land is different across China’s 30 provinces, and the characteristics of urban land use and economic development in eastern, central and western China should be considered to optimize strategies from the perspective of improving input and output indicators.

  • Orginal Article
    CHENG Linlin,ZHANG Junbiao,TIAN Yun,ZHOU Xiaoshi
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Here,we estimated agricultural carbon productivity of China’s 31 provinces from 2001 to 2012 and used the spatial auto-correlation Moran's index to investigate global differentiation characteristics,spatial correlation and clustering. We then employed the spatial Durbin model to explore influential factors and spatial effects of agricultural carbon productivity. The results show that agricultural carbon productivity in all of China’s 31 provinces increased during the sample period,and except for some provinces,provincial agricultural carbon productivity is in line with regional economic development levels. Inter-regional agricultural carbon productivity has a tendency to be heterogeneous,while the agricultural carbon productivity of different provinces in the same region is being homogenized. The differentiation and polarization phenomena of agricultural carbon productivity among different regions are relatively serious. Spatial auto-correlation of provincial agricultural carbon productivity is positive;provincial agricultural industrial structure has a negative influence on local agricultural carbon productivity. However,rural education level and agricultural openness have positive influences. The influence of agricultural economic development level,agricultural calamity degree and agricultural public investment derived from government is not evident. Provincial agricultural carbon productivity in China has spillover effects from the perspective of spatial factors. Rural education level and agricultural openness in one zone plays a role in the improvement of neighborhood agricultural carbon productivity,but,to a certain extent,agricultural economic development will inhibit development and the influence from agricultural economic development level,agricultural natural disaster and agricultural public investment on neighborhood agricultural carbon productivity remains unclear.

  • Orginal Article
    ZHANG Xufang,YANG Hongqiang,ZHANG Xiaobiao
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Climate change is a serious environmental problems faced by human beings. Increasing the carbon sink of forests and the carbon storage of harvested wood products is an effective approach to alleviate the greenhouse effect. China’s forestry carbon pool consists of two subsystems including the forest carbon pool and harvested wood products carbon pool. This study analyzed the developmental level of the forestry carbon pool over the past 20 years by integrating methods including the biomass method,single index model,biomass consumption method and stock change approach. The study also predicted the development trend of the Chinese forestry carbon pool in the next 20 years based on GM(1,1)modeling. We found that in terms of the forest carbon pool subsystems,a trend of steady increases from 1989 to 2013 is evident. The carbon storage of the forest pool was 17.5 billion tons in 2013,approximately 50% more than in 1993. The accumulative carbon emissions from logging residues and forest fires was 10.82 and 88.66 million tons,respectively,accounting for 0.57% of the forest carbon pool. In terms of the harvested wood products carbon pool subsystem,a rapid increase in the past 20 years was found. The total and newly increased carbon stock of HWP was 0.9 billion and 50 million tons in 2013,respectively,equivalent to 2.21 and 3.22 times 1993 levels,respectively. In terms of the Chinese forestry carbon pool system,the carbon storage was 18.48 billion tons in 2013. Prediction based on the GM(1,1)model indicated that the carbon storage of the Chinese forestry carbon pool would grow steadily at a relatively high speed from 2014 to 2033. The carbon storage of Chinese forestry carbon pool will reach 27.8 billion tons in 2033,almost 2.05 times the 1993 level.

  • Orginal Article
    WEI Wei,ZHOU Xiaobo
    Download PDF ( ) HTML ( )   Knowledge map   Save

    The energy conservation and emission reduction thinking of local industrial enterprises and the policy choices of policymakers are linked closely with the direction of local technological change. In order to fit the industrial processes of different provinces, we established a CES production function and used panel data for provinces from 1993 to 2012. First, the KEL form of the CES production function is closer to the actual provincial industrial production situation; however, the KEL form should not be denied at a significance level of 10%. Second, the technological progress of some provinces such as Beijing and Shanghai shows up as capital enhanced and capital biased types, therefore these provinces are supposed to use non-energy factors as substitutions. That of some provinces such as Tianjin and Hebei shows up as energy enhanced and capital biased types, and it is suitable for these provinces to improve energy efficiency. Third, the technological progress of some provinces such as Jilin and Anhui manifests as capital enhanced and energy biased types, and thus these provinces need to engage in policy regarding energy research and development subsidies. Shanxi and Inner Mongolia manifests as energy enhanced and energy biased types, and it is necessary for them to adjust industrial structure and increase research subsidy and development to solve environmental issues.

  • Orginal Article
    WANG Juan,ZHAO Tao,ZHANG Xiaohu
    Download PDF ( ) HTML ( )   Knowledge map   Save

    As an energy-intensity sector, the industrial sector consumes 70% of energy and generates more than 50% of CO2 in China. According to data spanning 36 industrial sub-sectors from 2006 to 2012, we adopted a non-radial DEA model which combined Natural Disposability and Managerial Disposability to study energy and environmental unified efficiency. Input indicators including fixed assets, energy and labor were considered as inputs under Natural Disposability, and R&D investment was regarded as an input under Managerial Disposability. The government promotes R&D investment on energy-saving technology and equipment in the industrial sector in China’s National Plan on Climate Change. This study also verified whether R&D investment was effective for different industrial sub-sectors to reduce undesirable outputs based on DEA modeling. Truncated regression modeling was adopted to analyze factors driving energy and environmental unified efficiency. We found that thirty-two sub-sectors had great room to improve their energy and environmental performance except for four sub-sectors (e.g. tobacco products industry). The unified efficiency scores of three sub-sectors including the coal mining and washing industry, chemical raw materials and chemical products manufacturing industry and non-metallic mineral products industry were all below 0.8, while the non-metallic mineral industry was 0.472 in this case. In 2012, R&D investment was effective for 16 sectors including coal mining and washing industry. Energy mix, technological innovation and market competition had significant impacts on unified efficiency. The proportion of coal consumption had a negative influence on unified efficiency, and the relationship between the ratio of R&D investments and unified efficiency was positive.

  • Orginal Article
    LI Shaolin
    Download PDF ( ) HTML ( )   Knowledge map   Save

    The fossil energy substituted by new energy has become an important means of ‘fog and haze governance’, reaching broad consensus on energy saving and emission reduction policies around the world. Here we defined new energy generation inputs as four forms (installed capacity of solar energy, wind power, geothermal energy and biofuels production) and defined electricity from new energy as an output indicator. Based on balanced panel data from 2001 to 2012 for 23 countries we used the Bootstrap-DEA method to correctly calculate the comprehensive efficiency of new energy’s power generation, and used the Tobit Model to empirically analyze driving factors of efficiency. We found that the comprehensive efficiency of global new energy power generation is rising; carbon emissions do not constitute a forced mechanism of the efficiency of new energy power generation; the proportion of natural resource rent has positive effects on the efficiency of new energy power generation; the urbanization rate has hindered the efficiency of new energy power generation; and the higher the per capita income of a nation, the higher the efficiency of new energy power generation. Based on these findings we propose that more attention should be given to the coordination of policies between the expansion of installed capacity and acceleration of generating capacity in order to improve the power generation of installed capacity. Research and development should be increased for energy storage technology, giving full play to the advantage of regional natural resource endowments, in order to crack the bottlenecks of ‘abandoned wind power’ and ‘abandoned light power’.

  • Orginal Article
    XU Shichun,LIU Yuantao,LONG Ruyin
    Download PDF ( ) HTML ( )   Knowledge map   Save

    With rapid economic growth, Jiangsu province has consumed enormous energy and emitted a great deal of carbon dioxide. Under a policy of energy savings and emissions reduction, researching the main factors that influence energy consumption is significant for Jiangsu carrying out specific measures to curb environmental pollution. Based on input-output tables for 2002, 2007 and 2012, we used structure decomposition analysis to decompose the factors influencing fossil energy consumption in Jiangsu in order to determine which is the prominent factor increasing energy consumption. Our results revealed that the effect of economic growth on consumption, investment, export and selling were major factors increasing energy consumption, while the effect of changes in energy intensity was the dominant factor in reducing energy consumption; the technology effect inhibited energy consumption, but its effect was very small. For different industries, the effect of the change in energy intensity in agriculture and construction promoted energy consumption, while the technology effect trend in the construction and service industry was ‘backward’. Industry in Jiangsu was the main source of energy consumption, for sub-sectors among the industry, the manufacturing industry enhanced energy consumption. Energy saving policy and carbon emission reduction are discussed from the aspects of economic growth, energy intensity and technological advancement, optimizing the energy consumption structure of Jiangsu, minimizing high-carbon contained energy and increasing clean energy.

  • Orginal Article
    XUE Yongji,SUN Yutong
    HTML ( )   Knowledge map   Save

    With growing competition within recreational tourism based on natural resources, brand construction has become the main way to obtain a competitive advantage. Based on tourism with natural resources, tourist brand recognition and brand attitude were explored. In total, 450 tourists were invited to answer questionnaires about brand recognition, perceived quality and brand loyalty regarding recreational tourism for natural resources, and eight recreational tourism places were chosen as examples. With 328 valid tourist questionnaires conducted in Beijing, SEM (structural equation models) were used to test relationships between brand recognition, perceived quality and brand loyalty. All variables were measured by Likert-7 scales with mature scales as references. We found that brand awareness and reputation do not have a positive impact on brand loyalty for natural resource recreational tourism. Brand awareness has a negative impact on perceived quality and brand trust. Brand reputation has a negative impact on tourist perceived quality and brand trust. Brand awareness can indirectly reduce brand loyalty through brand trust. Brand awareness and brand reputation have no significant impact on brand loyalty via perceived quality. We conclude that brand recognition does not impact the brand loyalty of natural resource recreational tourism significantly because two dimensions of brand recognition do not positively impact brand loyalty. Further, perceived quality and brand trust cannot result in brand loyalty. Traditional brand theory cannot explain brand phenomena within natural resource recreational tourism, and innovation is required for brand construction across natural resource recreational tourism.

  • Orginal Article
    LUO Huimin,YU Zhonglei,ZHANG Hua
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Cultural and creative tourism destination,as a brand-new tourism destination,is defined as a synthesis intergrating creativity,culture,landscape and tourism services. The tourist satisfaction of cultural and creative tourism destinations based on cultural creative industries is conductive to the sustainable development of tourism. Here,based on the American Customer Satisfaction Index and partial least squares method,we construct an index system and evaluation model of tourist satisfaction for cultural and creative tourism destinations. We measure the tourist satisfaction of Tianzifang,M50 and Hongfang in Shanghai,China and identify those factors affecting tourist satisfaction. The results show that decisive factors influencing tourist satisfaction are theme features,creativity,culture and environment for exchanging culture and creation;inferior factors are shopping environment and sanitary conditions. From this pastern, we can see that the landscapes and services of tourism destinations are of great importance to tourist satisfaction, because they influence tourists' experience effects. Culture and creativity,as the core attraction of the destination,are also very important to tourist satisfaction. Overall,the three tourism destinations can basically meet the needs of tourists. Among three tourism destinations,the highest satisfaction index is at Tianzifang (3.649),the second is M50(3.609),followed by Hongfang(3.447). The IPA index shows that Tianzifang develops well,M50 and Hongfang should improve the shopping environment,and M50 should perfect the environment for exchanging culture and creation. Based on the above conclusions, we suggest that, in order to attract more tourists, cultural and creative tourism destinations should make good use of cultural resources and strengthen theme features. Further,it is necessary to improve tourism service facilities for the sake of better tourism environments.

  • Orginal Article
    HUANG Tai
    Download PDF ( ) HTML ( )   Knowledge map   Save

    Tourist flow potential is the fundamental basis for the spatial competition-cooperation and integration development of urban agglomerations. Based on the tourism demand and supply system we used GIS and an improved gravity model to study spatial structural change of tourist flow potential in Yangtze River Delta Urban Agglomerations for 2000 and 2010. We used the discrete index and Zipf fractal dimension to study specific degrees of change and grade differences in structure. We then used product-moment correlation and rank correlation coefficients to analyze the impact and differences on the change in main factors’ structure,such as level of tourism,population distribution and time accessibility. We found that the whole structure is an equalization of hierarchical structure characterized by diffusion:the diffused characteristic is obvious in Shanghai and Hangzhou,and the tourist flow potential of cities in the center of the Yangtze River Delta (e.g. Suzhou,Jiaxing,Changzhou and Wuxi)has improved. The distribution of tourist flow potential in the Yangtze River Delta is disequilibrium and multi-polar nuclei,and a core-edge mode is the basic model to explain the structure. The power-law distribution and fractal characteristics in the hierarchical order of the structure further strengthen that power law and fractal growth can be a common phenomenon in tourism. Level of tourism industry and ranked tourist flow potential were the most strongly correlated,and the impact of population distribution and time distance is general. The compactness and structural efficiency between impact factors systems are strengthening,illustrating that tourism service efficiency and competition structure in Yangtze River Delta metropolitan areas tend to optimize. The correlation between tourist flow potential and urban economic level is significant and increasing over time,indicating that economic level is an important factor impacting urban tourist flow potential.