Fuzzy Comprehensive Assessment of Transnational Operation Environment for Chinese Oil Companies

A comprehensive method was developed to assess the transnational operation environment in host countries for Chinese oil companies. This method includes an assessment criterion system of the environment, which is to be scored by the experts. Analytical Hierarchy Process （AHP） and fuzzy mathematical methods were used to make evaluation and get the assessment result and ranking of three host countries.

Application of the Fuzzy Comprehensive Assessment Technique to Optimal Selection of Pipeline Design Alternative

s: Regarding the influencing factors in an optimal selection of pipeline design alternative as fuzzy variables with different weights, a fuzzy comprehensive assessment was applied to an optimal selection of the design alternative. Giving the Lanzhou-Chengdu pipeline as an example to explain the process, the result shows that this method is acceptable.

Fuzzy Comprehensive Assessment Method to Determine Tectonic Stress Patterns

The tectonic stress patterns were determined by a fuzzy comprehensive assessment method. Data of in-situ survey and fault information were utilized in the method. First, by making pressure and tension in the directions of along-river, cross-river, shear clockwise, and shear counterclockwise , 26 types of tectonic stress patterns were presented. And the stress vector of each pattern was obtained with FE software by taking unit displacement as boundary load. Then, by taking the 26 types of tectonic stress patterns as index set and 3 main stresses as factor set and choosing various operators, comparison of directions of computational stress vector and survey stress vector was made and the most possible tectonic stress pattern was obtained. Taking the 26 types of tectonic stress patterns as index set and strike angle as factor set, comparison of relationships between formation of fault and tectonic stress was made,and the tectonic stress patterns were assessed with known fault information. By summarizing the above assessment results, the most impossible tectonic stress pattern was obtained . Finally an engineering case was quoted to validate that the method is more feasible and reliable than traditional empirical method.

Multi-Level Fuzzy Comprehensive Assessment of Tourism Resources in Laiyuan County of Hebei Province

The membership of every target and the mathematic model of multi-level fuzzy comprehensive assessment are set up by using fuzzy theories and means in this study.Tourism resources of main scenic spots areas in Laiyuan County of Hebei Province are evaluated and classified by applying the model.The results of evaluation indicate that 10 of these scenic spots such as Baoziwo and Qingyunfeng are grade A,and 6 of them such as Yunpan Valley and Xianrenqiao are grade B.The peak forest scenic area in the Baishishan Geological Park and Shipuxia Scenic Area are grade A,and Jumayuan Scenic Area is grade B.Furthermore,suggestions are put forward based on the scientific and feasible development of tourism resources.

Assessment of heavy metals in sediment in a heavily polluted urban river in the Chaohu Basin, China

The Nanfei River （Anhui Province, China） is a severely polluted urban river that flows into Chaohu Lake. In the present study, sediments were collected from the river and analyzed for their heavy metal contents. Multivariate statistics and the fuzzy comprehensive assessment method were used to determine the sources of pollution, the current pollution status, and spatial and temporal variations in heavy metal pollution in sediments. The concentrations of arsenic （As）, cadmium （Cd）, chromium （Cr）, copper （Cu）, mercury （Hg）, nickel （Ni）, lead （Pb）, and zinc （Zn） in sediments ranged from 5.67-113, 0.08-40.2, 41.6-524, 15.5-460, 0.03-4.84, 13.5-180, 18.8-250, and 47.9-1 996 mg/kg, and the average concentrations of each metal were 1.7, 38.7, 1.8, 5.5, l 8.8, 1.3, 2.5, and 11.1 times greater than the background values, respectively. Multivariate statistical analysis demonstrated that Hg, Cu, Cr, Cd, and Ni may have originated from industrial activities, whereas As and Pb came from agricultural activities. The fuzzy comprehensive assessment method, based on the fuzzy mathematics theory, was used to obtain a detailed assessment of the sediment quality in the Nanfei River watershed. The results indicated that the pollution was moderate in the downstream tributaries of the Nianbu and Dianbu Rivers, but was severe in the main channel of the Nanfei River and in the upstream tributaries of the Sill and Banqiao Rivers. Therefore, sediments in the Nanfei River watershed are heavily polluted and urgent measures should be taken to remedy the status.

Development and Application of Oil-Spill Risk Assessment Model for Offshore Pipeline

To the potential oil-spill risk caused by offshore pipeline more attention has been paid after the Dalian oil spill incident from oil-pipeline explosion. Since then an issue about how to prevent and control the sudden oil-spill from the offshore pipeline has been raised. In this paper, we proposed an optimized model to analyze the main causes(probability) of spill and the consequence with the fuzzy comprehensive assessment model. Considering the complicated assessment process for oil-spill, the assessment factor system involving the spill probability and consequence was established based on the operative manual and statistic leakage/damage data of offshore pipeline in order to estimate the integrated spill risk score automatically. The evaluated factors of spill probability could be grouped into five aspects: corrosion, fatigue, national damage, third party, and operational fault; the consequence evaluated factors of spill included hazard of oil and impact-controlling capability. With some modifications based on experts' opinions, each of the evaluated factors in our work was developed with a relative weight and evaluation criterion. A test example for an offshore pipeline in the Bohai waters was described to show how the model can be used for an actual case in more detail. By using the oil-spill risk assessment model, it is easy to determine the risk level associated with the ongoing activity and management level and hence to take the risk mitigation action immediately.

System Reliability Analysis of Offshore Strctures and Component Safety Rank Assessment

Offshore structures will encounter serious environmental load, so it is important to study the structural system reliability and to evaluate the structural component safety rank. In this paper, the bracnch-and-bound method is adopted to search the main failure path, and the Ditlevsen bound method is used to calculate the system failure probability. The structure is then assessed by the fuzzy comprehensive assessment method, which evaluates the structural component safety rank. The ultimate equation of the tubular cross- section is analyzed on the basis of ultimate stregnth analysis. The influence of effect coefficients on the structural system failure probability is investigated, and basic results are obtained. A general program for spatial frame structures by means of the above method is developed, and verified by the numerical examples.

PROCESSING PARAMETER OPTIMIZATION OF FDM BASED ON ROBUST DESIGN

The influence of processing parameters on the precision of parts fabricated by fused deposition modeling （FDM） technology is studied based on a series of performed experiments. Processing parameters of FDM in terms of wire-width compensation, extrusion velocity, filing velocity, and layer thickness are chosen as the control fac- tors. Robust design analysis and multi-index fuzzy comprehensive assessment method are used to obtain the opti- mal parameters. Results show that the influencing degrees of these four factors on the precision of as-processed parts are different. The optimizations of individual parameters and their combined effects are of the same impor- tance for a high precision manufacturing.

APPROACH FOR MODULE PARTITION OF BLOCKS IN SHIPBUILDING

To manage the complexities of hull module partitions, a new approach to the partitions of hierarchical modules for shipbuilding is proposed. Based on the assembly and manufacture process, the approach determines the hierarchy and basis of the module partition first, and then according to the type of connection between the parts of the block module, the degree of membership for the rational connection is gained and the fuzzy relation matrix between different parts is then established. The fuzzy clustering technique is used to partition the modules, and then the method of fuzzy comprehensive assessment is used to choose a relative reasonable scheme. A case study has been conducted, which proves that the approach is feasible and applicable; Especially it obtains the sub-module partition, which sets up the shipbuilding process at a higher-level assembly and has offered effective tools for the modular ship design.

Impact of environmental factors on water quality at multiple spatial scales and its spatial variation in Huai River Basin, China

Quantitative assessment of water quality and its spatial variation identification, as well as the discernment of primary factors affecting water quality are in its urgent in water environment management. In this study, four key water quality indicators,namely, ammonia nitrogen(NH_4^+-N), permanganate index(COD_(Mn)), total phosphorus(TP) and total nitrogen(TN) at 71 sampling sites were selected to evaluate water quality and its spatial variation identification. More concerns were emphasized on the anthropogenic factors(land use pattern) and natural factors(river density, elevation and precipitation) to quantify the overall water quality variations at different spatial scales. Results showed that the Yi-Shu-Si River sub-basin had a better water quality status than the Huai River sub-basin. The moderate polluted area nearly distributed in the upper and middle reaches of the Shaying River and Guo River. The high cluster centers which were surrounded with COD_(Mn), NH_4^+-N, TN and TP mainly also distributed in the upper and middle reaches of the Shaying River and Guo River. Redundancy analysis showed that the 200 m buffer area acted as the most sensitive area, which was easily subjected to pollution. The precipitation was identified as the most important variables among all the studied hydrological units, followed by farmland, urban land or elevation. The point source pollution was still existed although the non-point source pollution was also identified. The urban surface runoff pollution was severer than farmland fertilizer loss at the sub-basin scale in flood season, while the farmland showed "small-scale" effects for explaining overall water quality variations. This research is helpful for identifying the overall water quality variations from the scale-process interactions and providing a scientific basis for pollution control and decision making for the Huai River Basin.

Spatio-temporal variations of water quality in Yuqiao Reservoir Basin, North China

Fuzzy comprehensive assessment and multivariate statistical techniques including cluster analysis, discriminant analysis, principal component analysis, and factor analysis were applied to analyze the water quality status of Yuqiao Reservoir Basin, North China, for assessing its spatio-temporal variations and identifying potential pollution sources. In this paper, we considered data for 14 water quality parameters collected during 1990–2004 at 7 water quality monitoring sites. The results of fuzzy comprehensive assessment revealed that water quality in Yuqiao Reservoir Basin showed a downtrend from 1990 to 2001 with fluctuation, and a slowly upward trend after 2001. The major water quality belonged to Class III and IV. Besides, hierarchical cluster analysis divided 7 monitoring sites into two groups （Group A and B）, and 12 months into three periods （low-flow （LF）, normal-flow （NF）, and high-flow （HF） period）. Temp, pH, SS, T-har, DO, NO3-N and TP were identified as significant variables affecting spatial variations, and Temp, pH and NO2-N were identified as significant variables affecting temporal variations by discriminant analysis. Factor analysis identified four latent pollution sources for water quality variations： nutrient pollution, organic pollution, inorganic pollution, and natural pollution. Moreover, for Group A regions, pollution inputs mainly came from domestic wastewater and industrial sewage. For Group B regions, it is more likely that water pollution resulted from the combined effects of domestic wastewater, hospital wastewater, agriculture runoff, and fishpond discharge, as well as the incoming water from upstream.