A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were anal...A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were analysed to set up the failure criterion of coal containing water and gas, which could describe the destruction rule of coal containing gas under the hydraulic measures more accurately. Based on the theory of transient flow and fluid grid, the numerical calculation model of turbulence formed by high pressure oscillating water jet was used. With the high speed photography test, dynamic evolution and pulsation characteristics of water jet water analysed which laid a foundation for mechanism analysis of rock damage under water jet. Wave equation of oscillating water jet slotting was established and the mechanism of coal damage by the impact stress wave under oscillation jet was revealed. These provide a new method to study the mechanism of porosity and crack damage under high pressure jet.Fracture criterion by jet slotting was established and mechanism of crack development controlled by crack zone between slots was found. The fractures were induced to extend along pre-set direction,instead of being controlled by original stress field. The model of gas migration through coal seams after the hydraulic measures for grid slotting and fracking was established. The key technology and equipment for grid slotting and fracking with high-pressure oscillating jet were developed and applied to coal mines in Chongqing and Henan in China. The results show that the gas permeability of coal seam is enhanced by three orders of magnitude, efficiency of roadway excavation and mining is improved by more than 57%and the cost of gas control is reduced by 50%.展开更多
Slotting strategy heavily influences the throughput and operational cost of automated order picking system with multiple dispenser types, which is called the complex automated order picking system （CAOPS）. Existing ...Slotting strategy heavily influences the throughput and operational cost of automated order picking system with multiple dispenser types, which is called the complex automated order picking system （CAOPS）. Existing research either focuses on one aspect of the slotting optimization problem or only considers one part of CAOPS, such as the Low-volume Dispensers, to develop corresponding slotting strategies. In order to provide a comprehensive and systemic approach, a fluid-based slotting strategy is proposed in this paper. The configuration of CAOPS is presented with specific reference to its fast-picking and restocking subsystems. Based on extended fluid model, a nonlinear mathematical programming model is developed to determine the optimal volume allotted to each stock keeping unit （SKU） in a certain mode by minimize the restocking cost of that mode. Conclusion from the allocation model is specified for the storage modules of high-volume dispensers and low-volume dispensers. Optimal allocation of storage resources in the fast-picking area of CAOPS is then discussed with the aim of identifying the optimal space of each picking mode. The SKU assignment problem referring to the total restocking cost of CAOPS is analyzed and a greedy heuristic with low time complexity is developed according to the characteristics of CAOPS. Real life application from the tobacco industry is presented in order to exemplify the proposed slotting strategy and assess the effectiveness of the developed methodology. Entry-item-quantity （EIQ） based experiential solutions and proposed-model-based near-optimal solutions are compared. The comparison results show that the proposed strategy generates a savings of over 18% referring to the total restocking cost over one-year period. The strategy proposed in this paper, which can handle the multiple dispenser types, provides a practical quantitative slotting method for CAOPS and can help picking-system-designers make slotting decisions efficiently and effectively.展开更多
Hydraulic slotting in a gas drainage borehole is an effective method of enhancing gas drainage perfor- mance. However, it frequently occurs that a large amount of slotting products （mainly the coal slurry and gas） i...Hydraulic slotting in a gas drainage borehole is an effective method of enhancing gas drainage perfor- mance. However, it frequently occurs that a large amount of slotting products （mainly the coal slurry and gas） intensely spurt out of the borehole during the slotting, which adversely affects the slotting efficiency. Despite extensive previous investigations on the mechanism and prevention-device design of the spurt during ordinary borehole drilling, a very few studies has focused on the spurt in the s Ottlng pro ] ＂ _ cess. The slotting spurt is mainly caused by two reasons： the coal and gas outburst in the borehole and the borehole deslagging blockage. This paper focuses on the second reason, and investigates the hydraulic deslagging flow patterns in the annular space between the drill pipe and borehole wall Results show that there are six deslagging flow patterns when the drill pipe is still： pure slurry flow, pure gas flow, bubble flow, intermittent flow, layering flow and annular flow. When the drill pipe rotates, each of those six flow patterns changes due to the Taylor vortex effect. Outcomes of this study could help to better understand the slotting-spurt mechanism and provide guidance on the anti-spurt strategies through eliminating the borehole deslagging blockage.展开更多
To solve the problems of rock strength increase caused by high in-situ stress,the stress release method with rock slot in the bottom hole by an ultra-high-pressure water jet is proposed.The stress conditions of bottom...To solve the problems of rock strength increase caused by high in-situ stress,the stress release method with rock slot in the bottom hole by an ultra-high-pressure water jet is proposed.The stress conditions of bottom hole rock,before and after slotting are analyzed and the stress release mechanism of slotting is clarified.The results show that the stress release by slotting is due to the coupling of three factors:the relief of horizontal stress,the stress concentration zone distancing away from the cutting face,and the increase of pore pressure caused by rock mass expansion;The stress concentration increases the effective stress of rock along the radial distance from O.6R to 1R(R is the radius of the well),and the presence of groove completely releases the stress,it also allows the stress concentration zone to be pushed away from the cutting face,while significantly lowering the value of stresses in the area the drilling bit acting,the maximum stress release efficiency can reach 80%.The effect of slotting characteristics on release efficiency is obvious when the groove location is near the borehole wall.With the increase of groove depth,the stress release efficiency is significantly increased,and the release range of effective stress is enlarged along the axial direction.Therefore,the stress release method and results of simulations in this paper have a guiding significance for best-improving rock-breaking efficiency and further understanding the technique.展开更多
Measured to control serious coal-gas outburst in coal seam were analyzed by theory and experimented in test site.A new technique to distress the coal-bed and drain methane,called hydraulic slotting,was described in de...Measured to control serious coal-gas outburst in coal seam were analyzed by theory and experimented in test site.A new technique to distress the coal-bed and drain methane,called hydraulic slotting,was described in detail,and the mechanism of hydrau- lic slotting was put forward and analyzed.The characteristic parameter of hydraulic slotting was given in Jiaozuo mining area and the characteristic of validity,adaptability and secu- rity was evaluated.The results show that the stress surrounding the strata and the gas in coal seam is released efficiently and thoroughly while new techniques are taken,as slot- ting at heading face by high pressure large diameter jet.The resistance to coal and gas outbursts is increased dramatically once the area of slotting is increased to a certain size. In the process of driving 2 000 m tunnel by hydraulic slotting excavation,coal and gas outburst never occurre.The technique could be used to prevent and control potential coal-gas outburst in the proceeding of tunnel driving,and the speed tunneling could be as high as more than 2 times.展开更多
A slotting method for cosine gears was proposed by using the involute cutter based on the conjugate theories of digital surface and gear meshing. The slotting model between the cosine tooth surface represented by disc...A slotting method for cosine gears was proposed by using the involute cutter based on the conjugate theories of digital surface and gear meshing. The slotting model between the cosine tooth surface represented by discrete points and the cutter figuration determined by analytic function was built for their geometrical relationship and conjugate motion during the machining process. Conjugate points in the cutter section corresponding to the discrete points on the cosine gear tooth surface and the conjugate movements were solved. By using the flexible control of the CNC procedure, the active control of the cutting trace of the slotting cutter was accomplished and the envelop forming of the cosine gear was obtained. Based on the software C++ and Matlab, the computer aided manufacturing(CAM) system of the cosine gear was developed, and the simulation of the slotting process was accomplished. Several examples were provided to illustrate the approach. The result of the simulation demonstrates that the proposed slotting method is feasible.展开更多
Many difficult-to-cut materials such as Ni-base super alloy, titanium alloy, and austenite stainless steel which are used extensively in aerospace generally have high strength-to-weight ratios, high corrosion resistan...Many difficult-to-cut materials such as Ni-base super alloy, titanium alloy, and austenite stainless steel which are used extensively in aerospace generally have high strength-to-weight ratios, high corrosion resistance, high strength retention ability at elevated temperatures, and low thermal conductivity. These characteristics can result in uneven tool wear and chatter vibration. Therefore, determining the appropriate end-milling conditions is more difficult for difficult-to-cut materials than for other materials. There has been much research on the high-speed milling of difficult-to-cut materials, and effective end-milling conditions, end-mill tool shapes, and processing methods have been reported. In addition, irregular pitch and lead end-mills with different helix angles have been developed by tool maker＇s to reduce chatter vibration, making it easier to perform high-speed milling. However, there have been few reports of slotting information useful for determining appropriate end-milling conditions and processing methods for Ni-base super alloy. The aim of this study is to derive end-milling condition with high efficiency grooving process for Ni-base super alloy （Inconel 718） sheet. Effects of cutting parameters were examined from the view point of cutting resistance, ＂tool tip maximum temperature and tool flank wear width. As a result from experiments, if the grooving process condition of axial depth of cut is smaller than other conditions on the same material removable rate value, it has been found that it is possible to reduce the tool tip maximum temperature and prolong the tool life.展开更多
The paper analyzes the characteristics and causes of formation of slotting allowances in China on the base of literature review on slotting allowances. The author believes that the government should take measures to m...The paper analyzes the characteristics and causes of formation of slotting allowances in China on the base of literature review on slotting allowances. The author believes that the government should take measures to make slotting allowances more reasonable and not to interfere necessary competition.展开更多
Hydraulic slotting can induce drill spray in a gassy,low permeability coal seam.This then influences subsequent gas extraction.This paper describes the drill spray phenomenon from a mechanical perspective and analyzes...Hydraulic slotting can induce drill spray in a gassy,low permeability coal seam.This then influences subsequent gas extraction.This paper describes the drill spray phenomenon from a mechanical perspective and analyzes the effects of water jet damage during slotting.A simulation of the stresses around the drill hole and slot was prepared using FLAC-3D code.It helps explain the induction of drill spray during hydraulic slotting.The stress concentration around the bore increases as the diameter of the hole increases.As the hole enlarges the variation in stress also increases,which introduces an instability into the coal.This allows easy breaking and removal of the coal.Destruction of the coal structure by the water jet is the major factor causing drill spray.Energy stored as either strain or gas pressure is released by the water jet and this causes the coal to fracture and be expelled from the hole.Field tests showed the effect on gas extraction after slotting with drill spray.The concentration of gas increases after drilling.Compared to conventional techniques,the hydraulic slotted bore gives a gas concentration three times higher and has an effective range twice as far.This makes the gas extraction process more efficient and allows reduced construction effort.展开更多
Plunge milling,which is recognized for its efficiency,has gradually been adopted for the roughing of integral impellers in recent years.However,several challenges persist,such as redundant tool paths,difficulties in m...Plunge milling,which is recognized for its efficiency,has gradually been adopted for the roughing of integral impellers in recent years.However,several challenges persist,such as redundant tool paths,difficulties in managing the Sudden Increase of Radial Depth(SIRD),and excessive residual material in the adjusted tool path by plunge milling,which collectively constrain the efficiency of the plunge milling process.To address these challenges,this study proposes a five-axis plunge milling method with double-row slotting tailored for integral impellers.This method segments the machining area based on the width of the impeller runner and utilizes various tools with different diameters to enhance machining efficiency.The plunge milling path is optimized to facilitate efficient material removal while maintaining cutting stability,which addresses issues related to cutting overload and chip accumulation.In addition,an efficient method for SIRD identification and exclusion is proposed to minimize residual material.Simulation and practical machining results confirm that the proposed plunge milling method with double-row slotting significantly improves machining efficiency,which achieves enhancements of over 1.5 times compared with traditional methods.展开更多
The concept of using blade slotting to suppress the large boundary layer separation of high aerodynamic loading low pressure turbine profile has been developed in Part 1.Calculated results highlight the inability perf...The concept of using blade slotting to suppress the large boundary layer separation of high aerodynamic loading low pressure turbine profile has been developed in Part 1.Calculated results highlight the inability performance accompanied with un-proper blade slotting at high Reynolds number,blade slotting optimization seems like compulsory.Meanwhile,to further dignify the rational for use of blade slotting,slotting position and its geometry needed to be optimized.Comparison of different slotting scheme calculation results promised that blade slotting parameter like outlet angle and outlet position are the most important parameters which must be investigated to satisfy the design purpose.展开更多
Hydraulic fracturing(HF)technology can safely and efficiently increase the permeability of coal seam,which is conducive to CBM exploration and prevent coal and gas outburst.However,conventional HF fractures tend to ex...Hydraulic fracturing(HF)technology can safely and efficiently increase the permeability of coal seam,which is conducive to CBM exploration and prevent coal and gas outburst.However,conventional HF fractures tend to expand in the direction of maximum principal stress,which may be inconsistent with the direction of fracturing required by the project.Therefore,the increased direction of coal seam permeability is different from that expected.To solve these problems,PFC2D software simulation is used to study directional hydraulic fracturing(DHF),that is the combination of slotting and hydraulic fracturing.The effects of different slotting angles(θ),different horizontal stress difference coefficients(K)and different injection pressures on DHF fracture propagation are analyzed.The results show that the DHF method can overcome the dominant effect of initial in-situ stress on the propagation direction of hydraulic fractures and control the propagation of fractures along and perpendicular to the slotting direction when θ,K and liquid injection pressure are small.When the DHF fracture is connected with manual slotting,the pressure will shake violently,and the fracturing curve presents a multi-peak type.The increase and decrease of particle pressure around the fracturing hole reflect the process of pressure accumulation and fracture propagation at the fracture tip respectively.Compared with conventional HF,DHF can not only shorten the fracturing time but also make the fracture network more complex,which is more conducive to gas flow.Under the action of in-situ stress,the stress between slots will increase to exceed the maximum horizontal principal stress.Moreover,with the change in fracturing time,the local stress of the model will also change.Hydraulic fractures are always expanding to the area with large local stress.The research results could provide certain help for DHF theoretical research and engineering application.展开更多
As the proportion of composite materials used in aircraft continues to increase, the electromagnetic Shielding Effectiveness (SE) of these materials becomes a critical factor in the electromagnetic safety design of ai...As the proportion of composite materials used in aircraft continues to increase, the electromagnetic Shielding Effectiveness (SE) of these materials becomes a critical factor in the electromagnetic safety design of aircraft structures. The assessment of electromagnetic SE for Slotted Composite Structures(SCSs) is particularly challenging due to their complex geometries and there remains a lack of suitable models for accurately predicting the SE performance of these intricate configurations. To address this issue, this paper introduces SCS-Net, a Deep Neural Network (DNN) method designed to accurately predict the SE of SCS. This method considers the impacts of various structural parameters, material properties and incident wave parameters on the SE of SCSs. In order to better model the SCS, an improved Nicolson-Ross-Weir (NRW) method is introduced in this paper to provide an equivalent flat structure for the SCS and to calculate the electromagnetic parameters of the equivalent structure. Additionally, the prediction of SE via DNNs is limited by insufficient test data, which hinders support for large-sample training. To address the issue of limited measured data, this paper develops a Measurement-Computation Fusion (MCF) dataset construction method. The predictions based on the simulation results show that the proposed method maintains an error of less than 0.07 dB within the 8–10 GHz frequency range. Furthermore, a new loss function based on the weighted L1-norm is established to improve the prediction accuracy for these parameters. Compared with traditional loss functions, the new loss function reduces the maximum prediction error for equivalent electromagnetic parameters by 47%. This method significantly improves the prediction accuracy of SCS-Net for measured data, with a maximum improvement of 23.88%. These findings demonstrate that the proposed method enables precise SE prediction and design for composite structures while reducing the number of test samples needed.展开更多
In wireless networks,the prioritized transmission scheme is essential for accommodating different priority classes of users sharing a common channel.In this paper,we propose a prioritized random access scheme based on...In wireless networks,the prioritized transmission scheme is essential for accommodating different priority classes of users sharing a common channel.In this paper,we propose a prioritized random access scheme based on compute-and-forward,referred to as expanding window sign-compute diversity slotted ALOHA(EW-SCDSA).We improve the expanding window technique and apply it to a high-throughput random access scheme,i.e.,the signcompute diversity slotted ALOHA(SCDSA)scheme,to implement prioritized random access.We analyze the probability of user resolution in each priority class utilizing a bipartite graph and derive the corresponding lower bounds,the effectiveness of which is validated through simulation experiments.Simulation results demonstrate that the EW-SCDSA scheme can provide heterogeneous reliability performance for various user priority classes and significantly outperforms the existing advanced prioritized random access scheme.展开更多
To enhance the quality factor and sensitivity of refractive index sensors,a feedback waveguide slot grating micro-ring resonator was proposed.An air-hole grating structure was introduced based on the slot micro-ring,u...To enhance the quality factor and sensitivity of refractive index sensors,a feedback waveguide slot grating micro-ring resonator was proposed.An air-hole grating structure was introduced based on the slot micro-ring,utilizing the reflection of the grating to achieve the electromagnetic-like induced transparency effect at different wavelengths.The high slope characteristics of the EIT-like effect enabled a higher quality factor and sensitivity.The transmission principle of the structure was analyzed using the transmission matrix method,and the transmission spectrum and mode field distribution were simulated using the finite-difference time-domain(FDTD)method,and the device structure parameters were adjusted for optimization.Simulation results show that the proposed structure achieves an EIT-like effect with a quality factor of 59267.5.In the analysis of refractive index sensing characteristics,the structure exhibits a sensitivity of 408.57 nm/RIU and a detection limit of 6.23×10^(-5) RIU.Therefore,the proposed structure achieved both a high quality factor and refractive index sensitivity,demonstrating excellent sensing performance for applications in environmental monitoring,biomedical fields,and other areas with broad market potential.展开更多
Intent detection and slot filling are two important components of natural language understanding.Because their relevance,joint training is often performed to improve performance.Existing studies mostly use a joint mod...Intent detection and slot filling are two important components of natural language understanding.Because their relevance,joint training is often performed to improve performance.Existing studies mostly use a joint model of multi-intent detection and slot-filling with unidirectional interaction,which improves the overall performance of the model by fusing the intent information in the slot-filling part.On this basis,in order to further improve the overall performance of the model by exploiting the correlation between the two,this paper proposes a joint multi-intent detection and slot-filling model based on a bidirectional interaction structure,which fuses the intent encoding information in the encoding part of slot filling and fuses the slot decoding information in the decoding part of intent detection.Experimental results on two public multi-intent joint training datasets,MixATIS and MixSNIPS,show that the bidirectional interaction structure proposed in this paper can effectively improve the performance of the joint model.In addition,in order to verify the generalization of the bidirectional interaction structure between intent and slot,a joint model for single-intent scenarios is proposed on the basis of the model in this paper.This model also achieves excellent performance on two public single-intent joint training datasets,CAIS and SNIPS.展开更多
Sesame is one of the eight major allergens that cause food allergies.Study of the epitopes of sesame allergens is important for understanding their sensitization mechanisms.Currently,less information is available on t...Sesame is one of the eight major allergens that cause food allergies.Study of the epitopes of sesame allergens is important for understanding their sensitization mechanisms.Currently,less information is available on the epitope studies of sesame allergens.In this study,we analyzed the molecular characteristics,structure and homology of Ses i 3,one of the important sesame allergens.We predicted the B-cell linear epitopes of Ses i 3 using bioinformatics tools and characterized them by slot blot immuno-microarrays technology.Eight peptides as B-cell linear epitopes of Ses i 3 were identified,in addition,key amino acids in these epitopes were predicted and leucine 422 was identified as a key amino acid.The present work will contribute to further understanding of the sesame allergen and provide some help in the prevention and treatment of sesame allergy.展开更多
Airports around the world commonly face challenges in managing airport slot allocation.Effective management of limited slot resources by civil aviation authority often requires redistributing requested slots among air...Airports around the world commonly face challenges in managing airport slot allocation.Effective management of limited slot resources by civil aviation authority often requires redistributing requested slots among airlines.The allocation process must operate within the prescribed capacity limits of the airport while adhering to established priorities and regulations.Additionally,ensuring market fairness is a key objective,as the value of airport slots plays a significant role in the adjustment process.This transforms the traditional time-shift-based problem into a complex multi-objective optimization problem.Addressing such complications is of significant importance to airlines,airports,and passengers alike.Due to the complexity of fairness metrics,traditional integer programming models encounter difficulties in finding effective solutions.This study proposes a neighborhood search strategy to tackle the single airport slot allocation,making it adaptable to both static and rolling capacity scenarios.Two Genetic Algorithms(GAs)are introduced,corresponding to time adjustment and sequence adjustment strategies,respectively.The GA based on the time adjustment strategy demonstrates high robustness,while the sequence adjustment strategy builds upon this GA to develop a simple heuristic algorithm that offers rapid convergence.Case studies conducted at seven airports in China confirm that all three algorithms yield high-quality adjustment solutions suitable for the majority of applications.Further,Pareto analysis reveals that these algorithms effectively balance the adjustment shifts and fairness metrics,demonstrating high practical value and broad applicability.展开更多
To enable efficient sharing of unbounded streaming data,this paper introduces blockchain technology into traditional cloud data,proposing a hybrid on-chain/off-chain storage model.We design a real-time verifiable data...To enable efficient sharing of unbounded streaming data,this paper introduces blockchain technology into traditional cloud data,proposing a hybrid on-chain/off-chain storage model.We design a real-time verifiable data structure that is more suitable for streaming data to achieve efficient real-time verifiability for streaming data.Based on the notch gate hash function and vector commitment,an adaptive notch gate hash tree structure is constructed,and an efficient real-time verifiable data structure for on-chain and off-chain stream data is proposed.The structure binds dynamic root nodes sequentially to ordered leaf nodes in its child nodes.Only the vector commitment of the dynamic root node is stored on the chain,and the complete data structure is stored off-chain.This structure ensures tamperproofing against malicious off-chain cloud servers of off-chain cloud servers.Preserves storage scalability space,realizes the immediate verification of stream data upon arrival,and the computational overhead of on-chain and off-chain hybrid storage verification is only related to the current data volume,which is more practical when dealing with stream data with unpredictable data volume.We formalize this as an efficient real-time verification scheme for stream data in on-chain and off-chain hybrid storage.Finally,the technology’s security and performance were empirically validated through rigorous analysis.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51374258,51504046,51404045)Program for Changjiang Scholars and Innovative Research Team in University of China(No.IRT13043)the National Basic Research Program of China(No.2014CB239206)
文摘A method of hydraulic grid slotting and hydraulic fracturing was proposed to enhance the permeability of low permeability coal seam in China. Micro-structural development and strength characteristics of coal were analysed to set up the failure criterion of coal containing water and gas, which could describe the destruction rule of coal containing gas under the hydraulic measures more accurately. Based on the theory of transient flow and fluid grid, the numerical calculation model of turbulence formed by high pressure oscillating water jet was used. With the high speed photography test, dynamic evolution and pulsation characteristics of water jet water analysed which laid a foundation for mechanism analysis of rock damage under water jet. Wave equation of oscillating water jet slotting was established and the mechanism of coal damage by the impact stress wave under oscillation jet was revealed. These provide a new method to study the mechanism of porosity and crack damage under high pressure jet.Fracture criterion by jet slotting was established and mechanism of crack development controlled by crack zone between slots was found. The fractures were induced to extend along pre-set direction,instead of being controlled by original stress field. The model of gas migration through coal seams after the hydraulic measures for grid slotting and fracking was established. The key technology and equipment for grid slotting and fracking with high-pressure oscillating jet were developed and applied to coal mines in Chongqing and Henan in China. The results show that the gas permeability of coal seam is enhanced by three orders of magnitude, efficiency of roadway excavation and mining is improved by more than 57%and the cost of gas control is reduced by 50%.
基金supported by China Scholarship Council (Grant No.2007102074)National Natural Science Foundation of China (Grant No.50175064)+2 种基金Georgia Institute of Technology Visiting Research EngineerProgram of the United States (Grant No. 2401247)Graduate InnovationFoundation of Shandong University, China (Grant No. yzc09066)Costal International Logistics Company of the United States (Project No.20080727)
文摘Slotting strategy heavily influences the throughput and operational cost of automated order picking system with multiple dispenser types, which is called the complex automated order picking system （CAOPS）. Existing research either focuses on one aspect of the slotting optimization problem or only considers one part of CAOPS, such as the Low-volume Dispensers, to develop corresponding slotting strategies. In order to provide a comprehensive and systemic approach, a fluid-based slotting strategy is proposed in this paper. The configuration of CAOPS is presented with specific reference to its fast-picking and restocking subsystems. Based on extended fluid model, a nonlinear mathematical programming model is developed to determine the optimal volume allotted to each stock keeping unit （SKU） in a certain mode by minimize the restocking cost of that mode. Conclusion from the allocation model is specified for the storage modules of high-volume dispensers and low-volume dispensers. Optimal allocation of storage resources in the fast-picking area of CAOPS is then discussed with the aim of identifying the optimal space of each picking mode. The SKU assignment problem referring to the total restocking cost of CAOPS is analyzed and a greedy heuristic with low time complexity is developed according to the characteristics of CAOPS. Real life application from the tobacco industry is presented in order to exemplify the proposed slotting strategy and assess the effectiveness of the developed methodology. Entry-item-quantity （EIQ） based experiential solutions and proposed-model-based near-optimal solutions are compared. The comparison results show that the proposed strategy generates a savings of over 18% referring to the total restocking cost over one-year period. The strategy proposed in this paper, which can handle the multiple dispenser types, provides a practical quantitative slotting method for CAOPS and can help picking-system-designers make slotting decisions efficiently and effectively.
文摘Hydraulic slotting in a gas drainage borehole is an effective method of enhancing gas drainage perfor- mance. However, it frequently occurs that a large amount of slotting products （mainly the coal slurry and gas） intensely spurt out of the borehole during the slotting, which adversely affects the slotting efficiency. Despite extensive previous investigations on the mechanism and prevention-device design of the spurt during ordinary borehole drilling, a very few studies has focused on the spurt in the s Ottlng pro ] ＂ _ cess. The slotting spurt is mainly caused by two reasons： the coal and gas outburst in the borehole and the borehole deslagging blockage. This paper focuses on the second reason, and investigates the hydraulic deslagging flow patterns in the annular space between the drill pipe and borehole wall Results show that there are six deslagging flow patterns when the drill pipe is still： pure slurry flow, pure gas flow, bubble flow, intermittent flow, layering flow and annular flow. When the drill pipe rotates, each of those six flow patterns changes due to the Taylor vortex effect. Outcomes of this study could help to better understand the slotting-spurt mechanism and provide guidance on the anti-spurt strategies through eliminating the borehole deslagging blockage.
基金support of the National Key Research and Development Program of China(2021YFE0111400)the Shandong provincial natural science foundation(No.ZR2019MEE120)the horizon programme of the EU's funding of the ORCH YD project,EU-H2020(101006752-ORCHYD).
文摘To solve the problems of rock strength increase caused by high in-situ stress,the stress release method with rock slot in the bottom hole by an ultra-high-pressure water jet is proposed.The stress conditions of bottom hole rock,before and after slotting are analyzed and the stress release mechanism of slotting is clarified.The results show that the stress release by slotting is due to the coupling of three factors:the relief of horizontal stress,the stress concentration zone distancing away from the cutting face,and the increase of pore pressure caused by rock mass expansion;The stress concentration increases the effective stress of rock along the radial distance from O.6R to 1R(R is the radius of the well),and the presence of groove completely releases the stress,it also allows the stress concentration zone to be pushed away from the cutting face,while significantly lowering the value of stresses in the area the drilling bit acting,the maximum stress release efficiency can reach 80%.The effect of slotting characteristics on release efficiency is obvious when the groove location is near the borehole wall.With the increase of groove depth,the stress release efficiency is significantly increased,and the release range of effective stress is enlarged along the axial direction.Therefore,the stress release method and results of simulations in this paper have a guiding significance for best-improving rock-breaking efficiency and further understanding the technique.
基金National Nature Science Foundation of China(50534070)International Science and Technology Cooperation and Communion Key Project of Ministry Science and Technology of China(2005DFA61030)+1 种基金Natural Science Foundation of Henan Province(200510460014)Coal Mine Gas and Fire Prevention and Control Key Laboratory Foundation of Henan Province(HKLGF200708)
文摘Measured to control serious coal-gas outburst in coal seam were analyzed by theory and experimented in test site.A new technique to distress the coal-bed and drain methane,called hydraulic slotting,was described in detail,and the mechanism of hydrau- lic slotting was put forward and analyzed.The characteristic parameter of hydraulic slotting was given in Jiaozuo mining area and the characteristic of validity,adaptability and secu- rity was evaluated.The results show that the stress surrounding the strata and the gas in coal seam is released efficiently and thoroughly while new techniques are taken,as slot- ting at heading face by high pressure large diameter jet.The resistance to coal and gas outbursts is increased dramatically once the area of slotting is increased to a certain size. In the process of driving 2 000 m tunnel by hydraulic slotting excavation,coal and gas outburst never occurre.The technique could be used to prevent and control potential coal-gas outburst in the proceeding of tunnel driving,and the speed tunneling could be as high as more than 2 times.
基金Projects(51205335,50975242,51375411) supported by the National Natural Science Foundation of ChinaProject(2013J01209) supported by the Natural Science Foundation of Fujian Province,China
文摘A slotting method for cosine gears was proposed by using the involute cutter based on the conjugate theories of digital surface and gear meshing. The slotting model between the cosine tooth surface represented by discrete points and the cutter figuration determined by analytic function was built for their geometrical relationship and conjugate motion during the machining process. Conjugate points in the cutter section corresponding to the discrete points on the cosine gear tooth surface and the conjugate movements were solved. By using the flexible control of the CNC procedure, the active control of the cutting trace of the slotting cutter was accomplished and the envelop forming of the cosine gear was obtained. Based on the software C++ and Matlab, the computer aided manufacturing(CAM) system of the cosine gear was developed, and the simulation of the slotting process was accomplished. Several examples were provided to illustrate the approach. The result of the simulation demonstrates that the proposed slotting method is feasible.
文摘Many difficult-to-cut materials such as Ni-base super alloy, titanium alloy, and austenite stainless steel which are used extensively in aerospace generally have high strength-to-weight ratios, high corrosion resistance, high strength retention ability at elevated temperatures, and low thermal conductivity. These characteristics can result in uneven tool wear and chatter vibration. Therefore, determining the appropriate end-milling conditions is more difficult for difficult-to-cut materials than for other materials. There has been much research on the high-speed milling of difficult-to-cut materials, and effective end-milling conditions, end-mill tool shapes, and processing methods have been reported. In addition, irregular pitch and lead end-mills with different helix angles have been developed by tool maker＇s to reduce chatter vibration, making it easier to perform high-speed milling. However, there have been few reports of slotting information useful for determining appropriate end-milling conditions and processing methods for Ni-base super alloy. The aim of this study is to derive end-milling condition with high efficiency grooving process for Ni-base super alloy （Inconel 718） sheet. Effects of cutting parameters were examined from the view point of cutting resistance, ＂tool tip maximum temperature and tool flank wear width. As a result from experiments, if the grooving process condition of axial depth of cut is smaller than other conditions on the same material removable rate value, it has been found that it is possible to reduce the tool tip maximum temperature and prolong the tool life.
文摘The paper analyzes the characteristics and causes of formation of slotting allowances in China on the base of literature review on slotting allowances. The author believes that the government should take measures to make slotting allowances more reasonable and not to interfere necessary competition.
基金support provided by the State Key Basic Research Program of China(No.2011CB201205)the National Natural Science Foundation of China(No.51074161)+3 种基金the National Science and Technology Support Program(No.2012BAK04B07)the project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(No.CXZZ12_0958)the Open Foundation project of Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal Mines(201201)support for the field application and tests of the technology
文摘Hydraulic slotting can induce drill spray in a gassy,low permeability coal seam.This then influences subsequent gas extraction.This paper describes the drill spray phenomenon from a mechanical perspective and analyzes the effects of water jet damage during slotting.A simulation of the stresses around the drill hole and slot was prepared using FLAC-3D code.It helps explain the induction of drill spray during hydraulic slotting.The stress concentration around the bore increases as the diameter of the hole increases.As the hole enlarges the variation in stress also increases,which introduces an instability into the coal.This allows easy breaking and removal of the coal.Destruction of the coal structure by the water jet is the major factor causing drill spray.Energy stored as either strain or gas pressure is released by the water jet and this causes the coal to fracture and be expelled from the hole.Field tests showed the effect on gas extraction after slotting with drill spray.The concentration of gas increases after drilling.Compared to conventional techniques,the hydraulic slotted bore gives a gas concentration three times higher and has an effective range twice as far.This makes the gas extraction process more efficient and allows reduced construction effort.
基金supported by the National Natural Science Foundation of China(Grant No.52075076).
文摘Plunge milling,which is recognized for its efficiency,has gradually been adopted for the roughing of integral impellers in recent years.However,several challenges persist,such as redundant tool paths,difficulties in managing the Sudden Increase of Radial Depth(SIRD),and excessive residual material in the adjusted tool path by plunge milling,which collectively constrain the efficiency of the plunge milling process.To address these challenges,this study proposes a five-axis plunge milling method with double-row slotting tailored for integral impellers.This method segments the machining area based on the width of the impeller runner and utilizes various tools with different diameters to enhance machining efficiency.The plunge milling path is optimized to facilitate efficient material removal while maintaining cutting stability,which addresses issues related to cutting overload and chip accumulation.In addition,an efficient method for SIRD identification and exclusion is proposed to minimize residual material.Simulation and practical machining results confirm that the proposed plunge milling method with double-row slotting significantly improves machining efficiency,which achieves enhancements of over 1.5 times compared with traditional methods.
基金provided by the Supercomputing Center of Chinese Academy of Sciences and the sponsorship of National Natural Science Foundation of China
文摘The concept of using blade slotting to suppress the large boundary layer separation of high aerodynamic loading low pressure turbine profile has been developed in Part 1.Calculated results highlight the inability performance accompanied with un-proper blade slotting at high Reynolds number,blade slotting optimization seems like compulsory.Meanwhile,to further dignify the rational for use of blade slotting,slotting position and its geometry needed to be optimized.Comparison of different slotting scheme calculation results promised that blade slotting parameter like outlet angle and outlet position are the most important parameters which must be investigated to satisfy the design purpose.
基金supported by National Natural Science Foundation of China(52130409,52004291,51874314)the Fundamental Research Funds for the Central Universities(2022YJSAQ03,2022XJAQ02).
文摘Hydraulic fracturing(HF)technology can safely and efficiently increase the permeability of coal seam,which is conducive to CBM exploration and prevent coal and gas outburst.However,conventional HF fractures tend to expand in the direction of maximum principal stress,which may be inconsistent with the direction of fracturing required by the project.Therefore,the increased direction of coal seam permeability is different from that expected.To solve these problems,PFC2D software simulation is used to study directional hydraulic fracturing(DHF),that is the combination of slotting and hydraulic fracturing.The effects of different slotting angles(θ),different horizontal stress difference coefficients(K)and different injection pressures on DHF fracture propagation are analyzed.The results show that the DHF method can overcome the dominant effect of initial in-situ stress on the propagation direction of hydraulic fractures and control the propagation of fractures along and perpendicular to the slotting direction when θ,K and liquid injection pressure are small.When the DHF fracture is connected with manual slotting,the pressure will shake violently,and the fracturing curve presents a multi-peak type.The increase and decrease of particle pressure around the fracturing hole reflect the process of pressure accumulation and fracture propagation at the fracture tip respectively.Compared with conventional HF,DHF can not only shorten the fracturing time but also make the fracture network more complex,which is more conducive to gas flow.Under the action of in-situ stress,the stress between slots will increase to exceed the maximum horizontal principal stress.Moreover,with the change in fracturing time,the local stress of the model will also change.Hydraulic fractures are always expanding to the area with large local stress.The research results could provide certain help for DHF theoretical research and engineering application.
基金supported by the National Natural Science Foundation of China(Nos.62101020 and 62141405)the Special Scientific Research Project of Civil Aircraft,China(No.MJZ5-2N22).
文摘As the proportion of composite materials used in aircraft continues to increase, the electromagnetic Shielding Effectiveness (SE) of these materials becomes a critical factor in the electromagnetic safety design of aircraft structures. The assessment of electromagnetic SE for Slotted Composite Structures(SCSs) is particularly challenging due to their complex geometries and there remains a lack of suitable models for accurately predicting the SE performance of these intricate configurations. To address this issue, this paper introduces SCS-Net, a Deep Neural Network (DNN) method designed to accurately predict the SE of SCS. This method considers the impacts of various structural parameters, material properties and incident wave parameters on the SE of SCSs. In order to better model the SCS, an improved Nicolson-Ross-Weir (NRW) method is introduced in this paper to provide an equivalent flat structure for the SCS and to calculate the electromagnetic parameters of the equivalent structure. Additionally, the prediction of SE via DNNs is limited by insufficient test data, which hinders support for large-sample training. To address the issue of limited measured data, this paper develops a Measurement-Computation Fusion (MCF) dataset construction method. The predictions based on the simulation results show that the proposed method maintains an error of less than 0.07 dB within the 8–10 GHz frequency range. Furthermore, a new loss function based on the weighted L1-norm is established to improve the prediction accuracy for these parameters. Compared with traditional loss functions, the new loss function reduces the maximum prediction error for equivalent electromagnetic parameters by 47%. This method significantly improves the prediction accuracy of SCS-Net for measured data, with a maximum improvement of 23.88%. These findings demonstrate that the proposed method enables precise SE prediction and design for composite structures while reducing the number of test samples needed.
基金supported by the National Natural Science Foundation of China under Grant No.62301008China Postdoctoral Science Foundation under Grant No.2022M720272。
文摘In wireless networks,the prioritized transmission scheme is essential for accommodating different priority classes of users sharing a common channel.In this paper,we propose a prioritized random access scheme based on compute-and-forward,referred to as expanding window sign-compute diversity slotted ALOHA(EW-SCDSA).We improve the expanding window technique and apply it to a high-throughput random access scheme,i.e.,the signcompute diversity slotted ALOHA(SCDSA)scheme,to implement prioritized random access.We analyze the probability of user resolution in each priority class utilizing a bipartite graph and derive the corresponding lower bounds,the effectiveness of which is validated through simulation experiments.Simulation results demonstrate that the EW-SCDSA scheme can provide heterogeneous reliability performance for various user priority classes and significantly outperforms the existing advanced prioritized random access scheme.
基金supported by Natural Science Foundation of Gansu Province(NO.21JR7RA289)。
文摘To enhance the quality factor and sensitivity of refractive index sensors,a feedback waveguide slot grating micro-ring resonator was proposed.An air-hole grating structure was introduced based on the slot micro-ring,utilizing the reflection of the grating to achieve the electromagnetic-like induced transparency effect at different wavelengths.The high slope characteristics of the EIT-like effect enabled a higher quality factor and sensitivity.The transmission principle of the structure was analyzed using the transmission matrix method,and the transmission spectrum and mode field distribution were simulated using the finite-difference time-domain(FDTD)method,and the device structure parameters were adjusted for optimization.Simulation results show that the proposed structure achieves an EIT-like effect with a quality factor of 59267.5.In the analysis of refractive index sensing characteristics,the structure exhibits a sensitivity of 408.57 nm/RIU and a detection limit of 6.23×10^(-5) RIU.Therefore,the proposed structure achieved both a high quality factor and refractive index sensitivity,demonstrating excellent sensing performance for applications in environmental monitoring,biomedical fields,and other areas with broad market potential.
基金Supported by the National Nature Science Foundation of China(62462037,62462036)Project for Academic and Technical Leader in Major Disciplines in Jiangxi Province(20232BCJ22013)+1 种基金Jiangxi Provincial Natural Science Foundation(20242BAB26017,20232BAB202010)Jiangxi Province Graduate Innovation Fund Project(YC2023-S320)。
文摘Intent detection and slot filling are two important components of natural language understanding.Because their relevance,joint training is often performed to improve performance.Existing studies mostly use a joint model of multi-intent detection and slot-filling with unidirectional interaction,which improves the overall performance of the model by fusing the intent information in the slot-filling part.On this basis,in order to further improve the overall performance of the model by exploiting the correlation between the two,this paper proposes a joint multi-intent detection and slot-filling model based on a bidirectional interaction structure,which fuses the intent encoding information in the encoding part of slot filling and fuses the slot decoding information in the decoding part of intent detection.Experimental results on two public multi-intent joint training datasets,MixATIS and MixSNIPS,show that the bidirectional interaction structure proposed in this paper can effectively improve the performance of the joint model.In addition,in order to verify the generalization of the bidirectional interaction structure between intent and slot,a joint model for single-intent scenarios is proposed on the basis of the model in this paper.This model also achieves excellent performance on two public single-intent joint training datasets,CAIS and SNIPS.
基金supported by the Fundamental Research Funds for the Public Research Institutes of Chinese Academy of Inspection and Quarantine(2022JK04).
文摘Sesame is one of the eight major allergens that cause food allergies.Study of the epitopes of sesame allergens is important for understanding their sensitization mechanisms.Currently,less information is available on the epitope studies of sesame allergens.In this study,we analyzed the molecular characteristics,structure and homology of Ses i 3,one of the important sesame allergens.We predicted the B-cell linear epitopes of Ses i 3 using bioinformatics tools and characterized them by slot blot immuno-microarrays technology.Eight peptides as B-cell linear epitopes of Ses i 3 were identified,in addition,key amino acids in these epitopes were predicted and leucine 422 was identified as a key amino acid.The present work will contribute to further understanding of the sesame allergen and provide some help in the prevention and treatment of sesame allergy.
基金supported in part by the National Natural Science Foundation of China(Nos.62167003,52302421)in part by the Diversified Investment Fund of Tianjin,China(No.23JCQNJC00210)。
文摘Airports around the world commonly face challenges in managing airport slot allocation.Effective management of limited slot resources by civil aviation authority often requires redistributing requested slots among airlines.The allocation process must operate within the prescribed capacity limits of the airport while adhering to established priorities and regulations.Additionally,ensuring market fairness is a key objective,as the value of airport slots plays a significant role in the adjustment process.This transforms the traditional time-shift-based problem into a complex multi-objective optimization problem.Addressing such complications is of significant importance to airlines,airports,and passengers alike.Due to the complexity of fairness metrics,traditional integer programming models encounter difficulties in finding effective solutions.This study proposes a neighborhood search strategy to tackle the single airport slot allocation,making it adaptable to both static and rolling capacity scenarios.Two Genetic Algorithms(GAs)are introduced,corresponding to time adjustment and sequence adjustment strategies,respectively.The GA based on the time adjustment strategy demonstrates high robustness,while the sequence adjustment strategy builds upon this GA to develop a simple heuristic algorithm that offers rapid convergence.Case studies conducted at seven airports in China confirm that all three algorithms yield high-quality adjustment solutions suitable for the majority of applications.Further,Pareto analysis reveals that these algorithms effectively balance the adjustment shifts and fairness metrics,demonstrating high practical value and broad applicability.
基金supported by the National Cryptologic Science Fund of China(Grant No.2025NCSF02020)awarded to Yi Sunsupported by the Natural Science Foundation of Henan Province(Grant No.242300420297)awarded to Yi Sun。
文摘To enable efficient sharing of unbounded streaming data,this paper introduces blockchain technology into traditional cloud data,proposing a hybrid on-chain/off-chain storage model.We design a real-time verifiable data structure that is more suitable for streaming data to achieve efficient real-time verifiability for streaming data.Based on the notch gate hash function and vector commitment,an adaptive notch gate hash tree structure is constructed,and an efficient real-time verifiable data structure for on-chain and off-chain stream data is proposed.The structure binds dynamic root nodes sequentially to ordered leaf nodes in its child nodes.Only the vector commitment of the dynamic root node is stored on the chain,and the complete data structure is stored off-chain.This structure ensures tamperproofing against malicious off-chain cloud servers of off-chain cloud servers.Preserves storage scalability space,realizes the immediate verification of stream data upon arrival,and the computational overhead of on-chain and off-chain hybrid storage verification is only related to the current data volume,which is more practical when dealing with stream data with unpredictable data volume.We formalize this as an efficient real-time verification scheme for stream data in on-chain and off-chain hybrid storage.Finally,the technology’s security and performance were empirically validated through rigorous analysis.
