Study on determination of borehole drainage radius by gas content method

In order to determine the radius of borehole gas drainage, using five kinds of gas content under different conditions corresponding to the extraction rate were compared according to different drainage objectives, determine the need for gas drainage amount, according to a certain period of time the average single hole gas drainage quantity, calculate the number of drilling in the region need to be arranged, and then get the borehole gas drainage radius. Based on the actual investigation and comparison analysis, the effective radius of borehole gas drainage in certain extraction time is obtained. The results show that the method of gas content determination of drilling drainage radius is feasible

Roles of Two Interhelical Insertions in Catalase-peroxidase Catalysis: Tracing the Impact of Peripheral Protein Structures on Heme Enzyme Function

Monofunctional peroxidases and bifunctional catalase-peroxidases share almost superimposable active sites, yet peroxidases lack appreciable catalase activity. Moreover, catalase-peroxidases catalyze both catalase and peroxidase reactions with a single active site. Given that catalase-peroxidases have two extra interhelical insertions that connect the D and E helices (the DE insertion), and F and G helices (the FG insertion), it is rational to suggest that these two insertions may serve to fine-tune the active site for bifunctionality. To explore the roles of these two insertions, we produced variants of E. coli catalase-peroxidase (KatG) lacking either the DE insertion (KatG?DE), the FG insertion (KatG?FG), or both insertions (KatG?DE/FG). All variants retained peroxidase activity that was comparable or greater than that of wtKatG. However, KatG?FG retained only 0.2% catalase activity, whereas KatG?DE and KatG?DE/FG lost all catalase activity, indicating both insertions are critical for KatG bifunctional ability. KatG?FG absorption and EPR spectra suggested little change in heme coordination state occurred when FG insertion was removed. Kinetic parameters suggested that the FG insertion poises the active site geometrically or electronically to help peroxide substrates access to the active site. In contrast, KatG?DE appeared to have more hexa-coordinate heme species present, suggesting this insertion is important for maintaining the correct heme coordination environment. The kinetic parameters suggest that the DE insertion serves to regulate the access of reducing substrates to the heme edge. As a result, the rate limiting step of the KatG?DE peroxidase catalytic cycle changed from compound I reduction as for wtKatG to compound II reduction. This led to an increased propensity to the formation of compound III for KatG?DE. This phenomenon is also commonly observed in monofunctional peroxidases. This inactivation could be prevented by the reducing substrate due to its competition with H2O2 in reacting with compound II. Furthermore, the inactive compound III could also be rescued back to the catalytic cycle by reducing substrate cation radicals. Both insertions, despite of their peripheral positions to the active site, serve to fine-tune the active site for its bifunctional properties and cooperate with other peripheral protein structures to achieve the full catalytic potential of the catalase-peroxidases

A HYBRID SELF-ORGANIZING SCHEDULING METHOD FOR SHIPS IN RESTRICTED TWO-WAY WATERWAYS

Traffic conflicts between ships are one of the most important reasons causing delays in restricted waterways. Aiming to improve the traffic efficiency, a hybrid self-organizing scheduling (HSOS) method for restricted two-way waterways is proposed. Ship transportation system is treated as a distributive and self-organized system under uncertainties. Each ship makes the decision on when to enter the waterway and how to keep the safe distance between them, while the VTS center could manage the direction of traffic flow according to the navigation situations. In order to reduce the traffic conflict between the opposite directions, small ships are given higher priority than the large ships in the same direction. When the large ships are accumulating, they are given higher priority than small ships in the same direction. The large ships are delayed while small ships decrease the waiting time. The trade-off between small and large ships can enhance efficiency by accumulating the large ships. Comparing the results from HSOS with First Come First Served (FCFS), it can effectively reduce the average delays brought by large ships, especially at high arrival rates

Numerical analysis of pressure fluctuation in a multiphase rotodynamic pump with air–water two-phase flow

International audiencePressure fluctuation in single-phase pumps has been studied widely, while less attention has been paid to research on multiphase pumps that are commonly used in the petroleum chemical industry. Therefore, this study investigates the pressure fluctuation for a multiphase rotodynamic pump handling air–water two-phase flow. Simulations based on the Euler two-fluid model were carried out using ANSYS_CFX16.0 at different Inlet Gas Void Fractions (IGVFs) and various flow rate values. Under conditions of IGVF = 0% (pure water) and IGVF = 15%, the accuracy of the numerical method was tested by comparing the experimental data. The results showed that the rotor–stator interaction was still the main generation driver of pressure fluctuation in gas–liquid two-phase pumps. However, the fluctuation near the impeller outlet ascribe to the rotor–stator interaction was weakened by the complex gas–liquid flow. For the different IGVF, the variation trend of fluctuation was similar along the streamwise direction. That is, the fluctuation in the impeller increased before decreasing, while in the guide vane it decreased gradually. Also, the fluctuation in the guide vane was generally greater than for the impeller and the maximum amplitude appeared in the vicinity of guide vane inlet

Optimization design of electrode grid lines for busbar-less solar cells

The electrode grid lines are a critical component of solar cells, where power loss caused by grid shading and associated resistance significantly impacts cell performance. We establish a power loss model for busbar-less solar cells to optimize the parameters and layout of grid lines, and analyze the influence of grid number, width, and mesh density on the power loss. A comparative evaluation of conversion efficiency was conducted between two types of busbar-less solar cells, namely, pin-up module (PUM) and side-point module (SPM), and conventional H-pattern solar cells. The simulation results demonstrate that busbar-less solar cells exhibit superior performance compared to H-pattern cells: the PUM design achieves absolute efficiency improvements of 1.66% and 1.65% for its two layout conditions, and the SPM design shows a 1.64% enhancement. Furthermore, for a larger mesh unit, the PUM design exhibits a distinct advantage over the SPM in achieving higher efficiency

Research on Water Absorption and Frost Resistance of Concrete Coated with Different Impregnating Agents for Ballastless Track Structure

In consideration of performance requirement of ballastless track concrete in cold regions of China, 3 types of commercially available impregnating agents were employed to research their effect on water absorption and frozen resistance of concrete, containing silanes, potassium silicate and osmotic curing agent. The results presented that coating silanes was the most effective on the reduction of water absorption among all employed impregnating agents, because of the most significant character change of concrete surface from hydrophilicity to hydrophobicity which could be proved by the contact angle test of concrete. The promotion on frozen resistance of concrete was not as significant as that for water absorption by coating 3 commercially available types of impregnant agents, because of the spalling damage on concrete surface during the freezing-thawing cycles

Method and key technologies of underground and surface combined stepwise progressive anti-outburst for deep coal seam groups

Modern high-yield and high-efficiency mines still face the situation of tight replacement among roadway driving, mining and extraction, and put forward higher requirements for the regional scope and advanced time of outburst prevention and control technology. In order to break through the bottlenecks of the existing gas control technology system in the coordinated extraction of near/far coal seam groups and the step-by-step outburst prevention both on the surface and underground, the principle of “spatiotemporal extraction and step-by-step progression” for outburst prevention with the combination of surface and underground operations is systematically expounded. A three-dimensional prevention and control method of “surface advanced pre-extraction for outburst reduction – underground enhanced extraction for outburst elimination – coordinated governance of multiple coal seams” is constructed. By integrating the advantages of spatiotemporal advance of surface wells and the precise control ability of underground operations, a three-level progressive prevention and control system of mine-level regional pre-control, mining area-level coordinated governance and working face-level precise outburst elimination is formed. According to the different characteristics of near and far coal seam groups, the outburst prevention modes of “wide coverage by surface wells and efficient extraction underground” and “enhanced pressure relief underground and multi-source extraction by surface wells” are respectively proposed. By comprehensively using numerical simulation, theoretical analysis and field test methods, a parameter optimization technology for multi-branch horizontal wells with key elements such as the angle between the main well and branch wells and the number of branch wells is systematically constructed. A precise docking technology between surface multi-branch wells and underground directional boreholes is formed by integrating the spatial magnetic field induction model of horizontal well bits and the data of high-precision sensors. The coupling evolution law of the stress field, fracture field and gas seepage field is analyzed, and the distribution characteristics of gas enrichment target areas in deep coal seams are revealed. Combined with the geological conditions and the requirements of the spatiotemporal connection of extraction, the collaborative layout modes of “maximization of a single well area” and “intensive layout in the whole area” for multi-source well groups are proposed. The high-efficiency extraction technology for near coal seam groups is applied in Shaqu No.1 Coal Mine. The total gas production of three multi-branch horizontal wells SQN–0501 after one-year extraction is 7 273 175.4 m3, with an average daily gas production of about 20 000 m3. The key technology of pressure relief extraction for far coal seam groups is applied in Zhuji West Coal Mine. The surface wells have cumulatively extracted 7.283 million m3 of gas from the No.13–1 coal seam, with an extraction rate as high as 81.4%, and the residual gas content is significantly reduced. The effectiveness of this technical system in improving gas extraction efficiency and reducing outburst risks is verified, providing important technical support for the safe mining of deep coal seam groups

Visible-Light-Activated Molecular Nanomachines Kill Pancreatic Cancer Cells

Recently, synthetic molecular nanomachines (MNMs) that rotate unidirectionally in response to UV light excitation have been used to produce nanomechanical action on live cells to kill them through the drilling of holes in their cell membranes. In the work here, visible-light-absorbing MNMs are designed and synthesized to enable nanomechanical activation by 405 nm light, thereby using a wavelength of light that is less phototoxic than the previously employed UV wavelengths. Visible-light-absorbing MNMs that kill pancreatic cancer cells upon response to light activation are demonstrated. Evidence is presented to support the conclusion that MNMs do not kill cancer cells by the photothermal effect when used at low optical density. In addition, MNMs suppress the formation of reactive oxygen species, leaving nanomechanical action as the most plausible working mechanism for cell killing under the experimental conditions

Numerical analysis of pressure fluctuation in a multiphase rotodynamic pump with air–water two-phase flow

Pressure fluctuation in single-phase pumps has been studied widely, while less attention has been paid to research on multiphase pumps that are commonly used in the petroleum chemical industry. Therefore, this study investigates the pressure fluctuation for a multiphase rotodynamic pump handling air–water two-phase flow. Simulations based on the Euler two-fluid model were carried out using ANSYS_CFX16.0 at different Inlet Gas Void Fractions (IGVFs) and various flow rate values. Under conditions of IGVF = 0% (pure water) and IGVF = 15%, the accuracy of the numerical method was tested by comparing the experimental data. The results showed that the rotor–stator interaction was still the main generation driver of pressure fluctuation in gas–liquid two-phase pumps. However, the fluctuation near the impeller outlet ascribe to the rotor–stator interaction was weakened by the complex gas–liquid flow. For the different IGVF, the variation trend of fluctuation was similar along the streamwise direction. That is, the fluctuation in the impeller increased before decreasing, while in the guide vane it decreased gradually. Also, the fluctuation in the guide vane was generally greater than for the impeller and the maximum amplitude appeared in the vicinity of guide vane inlet