To ensure that the coal mine robot can effectively avoid the dangerous gas area for quick and safe operation, and Improving its intelligence, this paper presents a prediction method of HPSO-GNN to get more accurate prediction of the regional gasdistribution ahead 10m of coal mine robot, considered the main factors that affect the concentration of gas, such as temperature, wind speed and direction, distance and so on, and the basis is provided to avoid the coal mine robot enter the dangerous gas area. Experimental results show that the overall prediction accuracy of the HPSO-GNN prediction method is improved compared to the GNN prediction method. Gas area distribution maps of 10 meters in front of coal mine robot are drawn with the forecast data and actual data respectively, By comparison it can be found that the difference between HPSO-GNN forecasted gasdistribution areas and the measured gasdistribution areas are insignificant, the distribution characteristic and concentration contour are approximately in accordance with the measured values. Therefore, the prediction method proposed in this paper can accurately predict the gas concentration distribution area, and provides a basis for the coal mine robot to avoid the dangerous area of gas, thus avoiding the occurrence of the gas explosion caused by the mine robot itself or the ground friction sparks. This ensures the safety operation of the coal mine robot in the coal mine.
PEMFC performance is limited by different mass transport phenomena during operation as: mass transport (conduction and diffusion) of reactive gases, ionic species and products, electron conductivity and ionic conductivity. The reagents are distributed by conduction on the diffusion layer surface of electrodes through manufactured distribution channels in the polar plates. Subsequently, the reactive gases diffuse to the active layer, where the electro-chemical semi-reactions take place. However, geometry, size, diameter, porosity and other physical characteristics in the structural basic elements for fuel cells generate particularly effects on the Proton Exchange Membrane Fuel Cell (PEMFC) performance. This paper includes an experimental comparison between different structural PEMFC designs; These designs combining different distribution plates and GasDistribution Medias (GDM) in the PEMFC, by application of a 2 3 experimental design with 3 different membrane- electrodes assemblies and 3 cathodic pressure levels. The results show significant effects on the functionality and generated electrical power by the PEMFC directly related to mass transport conditions (including electron transport), depending on the combination, material nature, electrical and structural characteristics of applied materials.
The algorithm consists of three distinct phases, where the first phase selects all customers that can receive a relatively large delivery compared to the customer’s capacity, the relative delivery size. The second phase creates clusters of customers around the customers that require a delivery in the planning period: the ‘must-go’ customers. The third phase assigns all customers to a delivery day in the planning period, with the objective to minimize total distance between customers. The algorithm considers the impact of a certain delivery on future planning periods, by evaluating the relative delivery size of customers that do not require a delivery in the planning period: the ‘may-go’ customers. An equal workload balance improves the efficient use of the available resources. In the third phase, we also balance the workload on the short-term and the long-term, by adding a delivery volume constraint. This delivery volume constraint is connected to the vehicle capacity on a certain day. The maximum delivery volume for a planning period is calculated by averaging the forecasted weekly demand in the next n weeks. This moving average in demand flattens the demand curve and mitigates the seasonal peak. We test the algorithm with n equal to 13 and 26, where n equal to 26 flattens the curve more. We compare the results of the algorithm plans with plans created by planners at a gas company. These tests illustrate that the algorithm delivers 21% more volume per kilometre than the actual plans, and decreases costs for gasdistribution with at least 12% (the decrease in distribution costs due to fewer visits is not considered in this percentage). Additionally, all customers require fewer visits, which not only decreases distribution costs, but also improves customer satisfaction. The algorithm uses between 600 to 1.000 seconds to run, which is acceptable in a region with three depots, 3.000 customers, and a planning period of seven days. The four main benefits of the solution are:
Every pipe is connected to two nodes at its ends. In a pipe network system, pipes are the channels used to convey fluid from one location to another. The physical characteristics of a pipe include the length, inside diam- eter, roughness coefficient, and minor loss coefficient. The pipe roughness coefficient is associated with the pipe material and age. The minor loss coefficient is due to the fittings along the pipe. When fluid is conveyed through the pipe, hydraulic energy is lost due to the fric- tion between the moving fluid and the stationary pipe surface. This friction loss is a major energy loss in pipe flow and is a function of flow rate, pipe length, diame- ter, and roughness coefficient. In the paper of Manojlović et al. (1994), which deals with optimized design of a gas-distribution pipeline network in the town of Kragujevac in Serbia, the Darcy-Weisbach formula with incorporated friction factor developed by Schi- frison is applied. In the present practice, Renouard (1962) equation is used by the engineers from Serbia and other countries, such as France, Spain, Portugal, etc. Advantage of this or similar equations are to be ex- plained in further discussion. Previous calculation of the gas network of Kragujevac from 1994. is very similar with calculation of water distribution networks (Sorbu and Borza, 1997; Samani and Naeeni, 1996; Kim, 2007), and according to this fact some deviations are occurred in real conditions apropos calculated results.
fees turned out to be “0”. Third explanation is also not plausible as it is again very questionable whether or not gains from not paying USDC is more than the cost of setting up all natural gasdistribution infrastructure and supplying gas to consumers without any profit. Among four explanations, the final one is the one that sounds most convincing. However, there is nothing wrong with such a situation. If a distribution company sets up an importing company, imports gas via it, purchases gas from its importing company by proving that it is the most ‘economical’ source, and then distributes gas without any profits and finally makes profits from its importing business; let it do so.
To answer the abovementioned questions, we selected our strategy as a case study in NIGC and chose quantitative-qualitative (mixed methods) in a descriptive-correlational form. This study is based on the fact that the data collected from the audited financial statements of the NIGC affiliated companies were valid and reliable. Therefore, the researchers did not have any interference in controlling and changing the values of the variables. Hence, in terms of the choices, this study is a post-event descriptive research type. Furthermore, as the study had been requested by NIGC, it is an applied research in terms of the purpose. In fact its purpose is the development of implicational knowledge in a particular field and its results can are used in the performance evaluation of gasdistribution companies. The time horizon of this study for historical financial data is the cross-section which uses a three years’ scope from 2015 to 2017. Furthermore, the time horizon related to the identification of financial performance measurement indicators tailored for NIGC (interviews and paired comparison) was limited to 2017. The primary data and information of this research including information on the position and financial performance of gasdistribution companies have been collected from the audited financial statements (balance sheets, income statements, statement of cash flows, and complementary notes to these statements) and other related internal reports and documents of NIGC. In addition, the primary information needed to identify and determine the key financial indicators and criteria for the evaluation of financial performance of the population companies suited for NIGC have been gathered by interviewing directors and heads of the finance and accounting; budget and cost control; final and consolidated accounts; and financing and investment departments of the NIGC. In order to provide the final list of financial indicators and determine the priorities of these indicators, we used the paired comparison technique, and to analyze the data collected from the interview, descriptive (interpretive) analysis was used. Eventually,
Abstract: Natural gas production in Sub-Saharan West African is projected to grow annually by 5% from 2010 to 2040. The distribution of this gas is vital to economic growth in the sub region. Compressed Natural Gas (CNG) which is natural gas that has been compressed under high pressure and held in hard containers is proposed as an alternative method of natural gasdistribution option for the sub-region to pipeline and LNG options especially for short distances within marine environments. The economic prospects of marine distribution of CNG within the West African region was studied and compared to the present West African Gas Pipeline (WAGP) distribution option. A discounted cash flow model was used to compare the economic viability of both projects. The CNG project had higher net present value of $1914 compared to $695 for the WAGP project. Payback period of 4.7 years and 11 years were respectively obtained for the CNG and WAGP projects.
Another important parameter is gas flow distribution through the ESP. Ideally the gas flow should be uniformly distributed throughout the ESP (top to bottom, side to side). Actually, however, gas flow through the ESP is not evenly distributed, and ESP manufacturers settle for what they consider an acceptable variation. Standards recommended the Industrial Gas Cleaning Institute have been set for gas flow distribution. Based on a velocity sampling routine, 85% of the points should be within 15% of the average velocity and 99% should be within 1.4 times the average velocity. Generally, uneven gas flow through the ESP results in reduced performance because the reduction in collection efficiency in areas of high gas flow is not compensated for by the improved performance in areas of lower flow. Also, improper gasdistribution can also affect gas sneak age through the ESP. As stated earlier, good gasdistribution can be accomplished by using perforated plates in the inlet plenum and turning vanes in the ductwork.
In practice supply chain network configuration typically involves optimizing strategic decisions without considering their impact on all the tactical delivery planning and daily scheduling decisions. In this paper we optimize not only strategic decisions but also consider all tactical and operational decisions in the mathematical model for the network configuration. We specifically consider the integrated network design problem dedicated to the packaged gases distribution. The main goals for solving the integrated network design problem include determining the locations of the hubs and the filling plants, the production capacity of the filling plants, the primary and the secondary cylinders flows and the inventory of both the filling plants and the hubs. To solve it, we propose a mathematical model which combines both the location-routing and the location-inventory integrated models and approximates the routing cost used in both the integrated models. In order to solve real large-scale problems, we propose approximate decomposition based approach. We applied near-optimal and approximate approaches on 3 real-life test cases from packaged gases cylinder distribution. The obtained solutions are within an acceptable optimality gap from the optimal solutions. The results indicate that mono-approach and two-steps approaches are capable to generate good facility location solutions in a reasonable time and are comparable to near-optimal solutions on smaller test cases. The difference between mono-product and two-steps is that two-steps method provides a better estimate of tactical and operational costs. For large-scale test cases, it is hard to obtain near-optimal solutions whereas two-steps approximation can generate good solutions in an acceptable time. Therefore, near-optimal approach is suitable for smaller test cases and approximation approaches for large-scale test cases.
Cosmological theories of structure formation predict that matter accreting onto galaxy clusters should experience a shock, termed the “virial shock,” coinciding roughly with the virial radius of the cluster (e.g., Bertschinger 1985). Detection of such a shock around a cluster would serve as an important probe of cosmological infall and accretion. Previous work has examined the impact of shocks on relations between X-ray observables such as the luminosity-temperature relation (Cavaliere et al. 1997), but we will instead relate the physics of the shock and the dark matter content of the cluster in deriving families of gas density profiles.
In diesel motors, NOx arrangement is an exceedingly temperature-subordinate wonder and happens when the temperature in the ignition chamber surpasses 2000 K. Along these lines, with a specific end goal to lessen NOx emanations in the fumes, it is important to hold crest ignition temperatures under control. One basic method for diminishing the NOx discharge of a diesel motor is by late injection of fuel into the burning chamber. This system is powerful however builds fuel utilization by 10–15%, which requires the utilization of more successful NOx lessening methods like fumes gasdistribution (EGR). Re-circling some portion of the fumes gas helps in diminishing NOx, however obvious particulate outflows are seen at high loads, consequently there is an exchange off in the middle of NOx and smoke emission. To get most extreme advantage from this exchange off, a particulate trap may be utilized to lessen the measure of unburnt particulates in EGR, which thus diminish the particulate outflow too.
Bubble Columns are widely used in chemical, petrochemical, pharmaceutical, metallurgical industries as multiphase reactors and contactors because of their simple construction and ease of operation. The bubble column have no moving parts as compare with the conventional stirred tank reactors, the contact between two or more phases are more effective in bubble columns as compare to stirred tank reactors. The energy efficiency in bubble columns is high. However, their design and scale up is still a difficult task, due to the complex structure of the multiphase flow encountered in this type of equipment. The fluid dynamics of multiphase reactors is very complex and is usually described in terms of single parameters and phenomena, namely off bottom particle suspension, power consumption, mixing time of the liquid, solids distribution inside the column and efficiency of sample withdrawal for solid liquid systems and overall and local gas hold-up, ventilated cavities at the rear of the impeller blades, bubble size and bubble size distribution, liquid mixing time, gasdistribution in the vessel for gas-liquid systems .
Based on Darton's theory , in a typical fluidized bed with uniform gasdistribution, bubbles tend to coalesce and migrate towards the bed center. The distribution of gas bubbles over the bed cross-section can be modified using baffles. Jiang et al. investigated the effect of ring baffles in the performance of a circulating fluidized bed reactor  , assembled at different heights along the riser and found improvement in the solids holdup and ozone conversion in the gas phase of the riser, compared to the no baffle condition. They also showed that enhanced solids and radial gas mixing can be achieved by utilizing baffles. Sanchez used radioactive particle tracking to study the impact of ring baffles on the motion of wet agglomerates in a fluidized bed . The study aimed at improving the performance of the stripper of a commercial Fluid Coker TM and it was found that the baffles reduce fouling on the sheds of the stripper section by increasing the residence time of wet agglomerates above the baffle and ultimately reducing the amount of undesired vapors in the region that lead to fouling. However, the addition of fluxtubes to these baffles curtails the baffle performance. Wyatt et al.  designed a ring of frusto-conical baffles with fluxtubes (down-comers), to be assembled in the periphery of the reaction section of circulating fluidized bed reactors like Fluid Cokers. They employed Computational fluid dynamic (CFD) modelling to show that the presence of baffles reduced fouling of the stripper internals . Modelling also showed that the baffle enhances the yield of C 5 +
The fracture properties of fractured shale gas reservoirs have been characterized by many methods. For example, Crafton and Gunderson  used the high frequency single- phase flowback data to characterize fracture properties. Further, Williams-Kovacs et al.  developed a flowing material balance equation with single-phase flow. However, these single-phase flow models ignore the analysis for water flowback data. Their prediction accuracy thus was not well evaluated in the two-phase flow period and later stages. The immediate two-phase flow after the shut-in period was observed in the Barnett shale and the Marcellus shale . A transient flowing model considering the effect of two- phase flow after the hydraulic fracturing was also developed for gas production . This model further analyzes the response of transient pressure. Yang et al.  developed a semianalytical model to simulate the two-phase flow dur- ing the flowback period with complex fracture networks. They found that increasing the fracture network complexity is favorable to gas production enhancement. Ezulike and Dehghanpour  applied a dynamic relative permeability on the two-phase flow in the hydraulic fractures. Their results showed that the relative permeability varies with reservoir parameters in the early flowback period. Xu et al.  analyzed the mechanisms for flowback behaviors and put forward a material balance approach to estimate the effective fracture volume in the Horn River Basin. Ezulike et al.  developed a two-phase flowback tank model for estimating fracture pore volume independent of fracture geometry. Their results indicated that the effective fracture pore volume is the most sensitive to fracture pore volume compressibility. Alkouh et al.  provided an effective method to estimate fracture volume through the water flow- back and gas production data. Therefore, different methods have been used to characterize the fracture properties but the interaction between fracture flow and shale gas diffu- sion has not been considered in the two-phase flowback stage.
Among different types of gasifiers, moving-bed gasifier has the longest history and is the most widely used commercially. Some examples of moving-bed gasifier are high-pressure Lurgi dry ash gasifier, British Gas Lurgi (BGL) slagging gasifier, and low- pressure Wellman Balusha gasifier. Lurgi’s are the predominant gasifiers used by the South African Coal, Oil, and Gas Corporation (SASOL) to produces a variety of chemicals and syngas from coal. Although Lurgi is widely used, relatively low capacity and the inability to handle fine coal powders limit its application. On the other hand, BGL, co-developed by British Gas and Lurgi, is well fitted to anthracite, and there are commercial applications showing success.
The analysis on shale gas types and conditions (Table 3) by Zhang et al.  , and CBM resource evaluation results show that Shanxi formation of Late Paleozoic Permian in North China (Ordos Basin), Longtan Forma- tion of Upper Permian of Late Paleozoic and Xujiahe formation of Upper Triassic of Mesozoic in South Chi- na(Yangtze region), Shuixigou Group (Xishanyao for- mation) of Middle-Lower Jurassic of Mesozoic in Tur- pan-Hami Basin and Junggar Basin, and Qingyi period and Shahezi formation of Mesozoic of Cretaceous in Songliao basin contain unequal thickness coal strata; of them the coal seam and shale rich in organic matter are thick. These regions, with rich organic carbon content, high maturity, possess the basic conditions to generate shale gas and methane simultaneously, become the fa- vorable areas and layers to carry out combined research and development of shale gas and CBM.
In this paper, we will take the view that clusters form within the hierarchical merging scenario (Allison et al. 2009, 2010) and, together with gas not used in star formation, they form bound ob- jects. Observations show very few young clusters associated with natal gas older than ∼ 5 Myr (Lada & Lada 2003; Lada 2010). It is assumed that feedback from massive stars removes residual gas in a gas expulsion phase. This gas expulsion will significantly alter the potential felt by the stars and can result in the destruction of the cluster (e.g. Tutukov 1978; Hills 1980; Goodwin & Bastian 2006; Baumgardt & Kroupa 2007; Goodwin 2009). This is often cited as the cause of ‘infant mortality’: the apparently high destruction rate of young clusters 1 (e.g. Lada & Lada 2003).
In recent years many operators have combined these requirements by the use of innovative stockless depot techniques. These are most appropriate when a large number of delivery vehicles are required, possibly undertaking more than one trip per day. Two methods are available. The load of a trunk vehicle can be stripped and transferred direct to a number of waiting delivery round vehicles under cover. Alternatively, demountable bodies can be used which are left standing on legs at satellite depots ready loaded for delivery round vehicles. The Brewery case study was tested using estimated costs for the use of draw-bar vehicles fitted with demountable bodies, together with a network of satellite depots. In this case the results indicated that significant savings could be obtained from using such a system. Since completing our analysis, which confirmed in-house managerial assessments, the brewery has in fact converted part of their distribution system to the use of drawbar vehicles, eliminating inventory at two depots.