Structural Evaluation Method Research Articles

Application of nuclear magnetic resonance core logging technology in oil and gas exploration of deep/ultra deep low porosity and low permeability reservoirs

Abstract In order to improve the efficiency of deep/ultra deep oil and gas exploration decision-making and release production capacity, and to address the difficulties in implementing the physical and fluid properties of complex deep/ultra deep reservoirs, nuclear magnetic resonance logging technology is used to establish a permeability calculation method and a glutenite reservoir pore structure evaluation method so that the liquid production capacity of the reservoir is classified. Combing nuclear magnetic resonance logging with gas logging technology, an comprehensive hydrocarbon evaluation index SI is established to evaluate complex fluid properties. The results show that: (1) The permeability calculated by T2gm using nuclear magnetic resonance logging spectra is highly consistent with laboratory measurement results. (2) By combining the nuclear magnetic porosity and permeability of the test layer with the pore structure parameters calculated by nuclear magnetic, a classification standard for low porosity and low permeability glutenite reservoirs can be established, which can provide a preliminary evaluation of the reservoir’s liquid production capacity. (3) The comprehensive evaluation chart of nuclear magnetic resonance logging combining with gas logging can effectively distinguish oil layers, gas layers, and water layers, thereby distinguishing complex fluid properties. This research achievement is of great value for implementing the physical and fluid properties of deep/ultra deep complex reservoirs in Bohai Oilfield, and guiding efficient exploration and development operations.

Multifunctional carbomer based ferulic acid hydrogel promotes wound healing in radiation-induced skin injury by inactivating NLRP3 inflammasome

BackgroundRadiation-induced skin injury is a significant adverse reaction to radiotherapy. However, there is a lack of effective prevention and treatment methods for this complication. Ferulic acid (FA) has been identified as an effective anti-radiation agent. Conventional administrations of FA limit the reaching of it on skin. We aimed to develop a novel FA hydrogel to facilitate the use of FA in radiation-induced skin injury.MethodsWe cross-linked carbomer 940, a commonly used adjuvant, with FA at concentrations of 5%, 10%, and 15%. Sweep source optical coherence tomography system, a novel skin structure evaluation method, was applied to investigate the influence of FA on radiation-induced skin injury. Calcein-AM/PI staining, CCK8 assay, hemolysis test and scratch test were performed to investigate the biocompatibility of FA hydrogel. The reducibility of DPPH and ABTS radicals by FA hydrogel was also performed. HE staining, Masson staining, laser Doppler blood flow monitor, and OCT imaging system are used to evaluate the degree of skin tissue damage. Potential differentially expressed genes were screened via transcriptome analysis.ResultsGood biocompatibility and in vitro antioxidant ability of the FA hydrogels were observed. 10% FA hydrogel presented a better mechanical stability than 5% and 15% FA hydrogel. All three concentrations of FA remarkably promoted the recovery of radiation-induced skin injury by reducing inflammation, oxidative conidiation, skin blood flow, and accelerating skin tissue reconstruction, collagen deposition. FA hydrogel greatly inhibiting the levels of NLRP3, caspase-1, IL-18, pro-IL-1β and IL-1β in vivo and vitro levels through restraining the activation of NLRP3 inflammasome. Transcriptome analysis indicated that FA might regulate wound healing via targeting immune response, inflammatory response, cell migration, angiogenesis, hypoxia response, and cell matrix adhesion.ConclusionsThese findings suggest that the novel FA hydrogel is a promising therapeutic method for the prevention and treatment of radiation-induced skin injury patients.Graphical

Computational Fluid Dynamics Study on Bottom-Hole Multiphase Flow Fields Formed by Polycrystalline Diamond Compact Drill Bits in Foam Drilling

High-temperature geothermal wells frequently employ foam drilling fluids and Polycrystalline Diamond Compact (PDC) drill bits. Understanding the bottom-hole flow field of PDC drill bits in foam drilling is essential for accurately analyzing their hydraulic structure design. Based on computational fluid dynamics (CFD) and multiphase flow theory, this paper establishes a numerical simulation technique for gas-liquid-solid multiphase flow in foam drilling with PDC drill bits, combined with a qualitative and quantitative hydraulic structure evaluation method. This method is applied to simulate the bottom-hole flow field of a six-blade PDC drill bit. The results show that the flow velocity of the air phase in foam drilling fluid is generally higher than that of the water phase. Some blades’ cutting teeth exhibit poor cleaning and cooling effects, with individual cutting teeth showing signs of erosion damage and cuttings cross-flow between channels. To address these issues, optimizing the nozzle spray angle and channel design is necessary to improve hydraulic energy distribution, enhance drilling efficiency, and extend drill bit life. This study provides new ideas and methods for developing geothermal drilling technology in the numerical simulation of a gas-liquid-solid three-phase flow field. Additionally, the combined qualitative and quantitative evaluation method offers new insights and approaches for research and practice in drilling engineering.

An insight into structure-activity relationships in subclass IIb bacteriocins: Plantaricin EvF

This study reports the structure-activity relationships of a unique subclass IIb bacteriocin, plantaricin EvF, which consists of two peptide chains and possesses potent antimicrobial activity. Because the plantaricin Ev peptide chain lacks an α-helix structure, plantaricin EvF is unable to exert its antimicrobial activity through helix-helix interactions like typical subclass IIb bacteriocins. We have shown by various structural evaluation methods that plantaricin Ev can be stabilized by hydrogen bonding at amino acid residues R3, V12, and R13 to the N-terminal region of plantaricin F. This binding gives plantaricin EvF a special spade-shaped structure that exerts antimicrobial activity. In addition, the root-mean-square deviations (RMSDs) of the amino acid residues Y6, F8, and R13 of plantaricin Ev pre- and post-binding were 1.512, 1.723, and 1.369, respectively, indicating that they underwent large structural changes. The alanine scanning experiments demonstrated the important role of the above key amino acids in maintaining the structural integrity of plantaricin EvF. This study not only reveals the unique structural features of plantaricin EvF, but also provides an insight into the structure-activity relationships of subclass IIb bacteriocins.

Health assessment of TBM diversion tunnel structure based on AHP and AMV models

Health assessment is one of the important theoretical bases for deciding whether the diversion tunnel can operate safely and stably. A project of the TBM diversion tunnel is taken as the research object to ensure the normal operation of the diversion tunnel. Based on measured data and considering multiple safety aspects such as structural response, durability, and external factors of the diversion tunnel, a TBM diversion tunnel structural health evaluation index system is established. A new method for the TBM diversion tunnel structural health comprehensive evaluation based on Analytic Hierarchy Process-Matter Element Extension-Variable Weight Theory (AMV) is proposed to explore the impact of AMV fluctuation with the measured results of the indicators on the weight, closeness, and health grade of each evaluation index. The high sensitivity and high-risk evaluation indicators for the structural health of the diversion tunnels are identified. It is found that the variable weight varies with the changes in various indicator values, which can accurately evaluate the health status of tunnels in real-time. The characteristic values of the tunnel grade calculated by the AHP and the AMV are 1.589 and 1.695, respectively. The results of the corresponding interval diversion tunnel are the basic safety state of grade B. Except for the two evaluation indicators of concrete strength and slurry properties, the variable weight values and grade characteristic values of other evaluation indicators increase with the increase of indicator values. The four indicators of segment settlement, segment opening, segment misalignment, and segment cracks are more sensitive to the health of the TBM diversion tunnel. This AMV can accurately evaluate the health status of the diversion tunnel structure. The research results can provide references for later maintenance work and similar projects.

A Comparative Study of English General Education Curriculum System in Chinese and Japanese Universities

China and Japan are both East Asian countries with similar historical backgrounds and cultural origins, and they hold identical attitudes towards English language education in colleges and universities, i.e., improving the English language proficiency of the nationals has excellent advantages for individuals and the country, and the English language education in colleges and universities of the two countries is comparable in many aspects and can be borrowed from each other. This paper focuses on the curriculum system of liberal education in Chinese and Japanese universities and takes Peking University and the University of Tokyo as the objects of study. It compares and analyzes the similarities and differences between the liberal English education programs of the two universities regarding curriculum overview, curriculum objectives, curriculum structure, and curriculum evaluation methods. It analyzes and summarizes the characteristics of the two sides to enhance the strengths and avoid the shortcomings, to make up for the drawbacks of English liberal education in Chinese universities, and to harvest the usable experience.

The collapse evaluation method of steel moment-resisting frames based on dynamic increase factor

The collapse evaluation method of steel moment-resisting frames based on dynamic increase factor

The Optimization of Waterproof and Drainage Design and an Evaluation of the Structural Safety of Tunnels in Weak Watery Strata

The surrounding rock and high water pressure in weak watery strata have adverse effects on the mechanical properties of tunnel support structures. In order to optimize the anti-drainage design of tunnels in weak watery strata and evaluate their structural safety, this paper relies on the Taidacun Tunnel of the China–Laos Railway to carry out field monitoring research. A dual-field fluid–solid coupling calculation model is established to optimize the tunnel’s waterproof and drainage design, combined with a bending moment curvature model to evaluate structural safety. The main conclusions are as follows: Under the action of high water and soil pressure, the structural safety margin of the water-rich fine sand section of the Taidacun Tunnel is small, and waterproof and drainage design optimization is required. Combined with the proposed average pressure reduction coefficient, the influence of the water level and annular blind pipe spacing on the water pressure of the lining is proved, and then the optimal annular blind pipe spacing in the water-rich area of the tunnel is determined. A structural safety evaluation method based on the bending moment curvature model is proposed. Two models of elastic beam and moment–curvature beam are used to analyze the mechanical characteristics and optimization effects of the structure under optimal annular blind pipe spacing.

Traffic Speed Deflectometer for Network-Level Pavement Management in Tennessee

The traffic speed deflectometer (TSD) overcomes the limitations of the falling weight deflectometer (FWD) with respect to traffic interruption and test inefficiency and is considered the preferred method for network-level pavement structural evaluation. However, some challenges exist when applying the TSD to routine survey work. This study evaluated the long-term repeatability of TSDs and compared TSD measurements with FWD measurements to examine device-related errors in TSD measurements. In addition, a framework for incorporating TSD measurements into the pavement management system (PMS) was developed by introducing deflection bowl parameters (DBPs). All data analyses were based on TSD data collected in Tennessee. From the current study, the repeatability of the TSD has not been fully validated because of device-related errors. Since TSD measurements and FWD measurements are broadly similar, periodic validation of TSDs by FWDs is recommended for quality control. TSDs provide valuable information about pavement structural conditions that are not reliably or adequately reflected in the current PMS (which focuses mainly on pavement functional conditions). DBPs are a simple and fast method for making initial estimates of pavement structural conditions without the need for layer thickness. In the proposed DBP system, the surface curvature index (SCI_12) and D60 (TSD deflection at 60 in. before the load center) represent the structural strength of the asphalt layer and subgrade, respectively. The combination of pavement functional conditions and TSD-measured structural conditions (PMS+DBPs) may help to make more accurate predictions of pavement performance and to make more appropriate decisions on maintenance and rehabilitation strategies.

A residue-focused protein crystal structure evaluation method based on electron density

A residue-focused protein crystal structure evaluation method based on electron density

Dynamic risk analysis of accidents chain and system protection strategy based on complex network and node structure importance

Due to the increasing complexity and nonlinearity of complex industrial systems, traditional risk analysis methods have become inapplicable. A method of dynamic risk analysis and system protection based on complex networks and node structure importance was established. The effectiveness of this method is demonstrated through case studies, where we compare and analyze six protection strategies. In light of the topology and directivity of the accidents chain network (ACN) in the complex industrial system, a node structure importance evaluation method and an ACN evaluation method were established to measure the protection cost. An optimal protection strategy model with the protection cost constraint was proposed, and a study was carried out on the ACN of UHV converter transformer. The results show that ACN in UHV converter transformer belongs to a scale-free network. The structural importance evaluation method can identify the critical nodes in ACN, and better reflect the structural importance of nodes than the traditional degree indicator. Considering the dual objectives of the complex system, the optimal protection strategy proposed by the optimal protection model achieves better effect than other strategies, no matter how the protection cost factor and the protection cost budget coefficient change.

Enhancing Electron Conductivity and Electron Density of Single Atom Based Core-Shell Nanoboxes for High Redox Activity in Lithium Sulfur Batteries.

Herein, an integrated structure of single Fe atom doped core-shell carbon nanoboxes wrapped by self-growing carbon nanotubes (CNTs) is designed. Within the nanoboxes, the single Fe atom doped hollow cores are bonded to the shells via the carbon needles, which act as the highways for the electron transport between cores and shells. Moreover, the single Fe atom doped nanobox shells is further wrapped and connected by self-growing carbon nanotubes. Simultaneously, the needles and carbon nanotubes act as the highways for electron transport, which can improve the overall electron conductivity and electron density within the nanoboxes. Finite element analysis verifies the unique structure including both internal and external connections realize the integration of active sites in nano scale, and results in significant increase in electron transfer and the catalytic performance of Fe-N4 sites in both Li2 Sn lithiation and Li2 S delithiation. The Li-S batteries with the double-shelled single atom catalyst delivered the specific capacity of 702.2 mAh g-1 after 550 cycles at 1.0 C. The regional structure design and evaluation method provide a new strategy for the further development of single atom catalysts for more electrochemical processes.

Structural Behavior Prediction Model for Asphalt Pavements: A Deep Neural Network Approach

Abstract Structural behavior of pavements is assessed using various destructive and nondestructive tests, albeit they are found to be cost-intensive. There is a need to develop cost-effective structural condition evaluation methods that are scientifically sound so appropriate maintenance interventions can be performed at the right time. The objective of this research study was to develop a Deep Neural Network (DNN)–based approach to predict pavement structural condition using functional, traffic, and climatic characteristics. A DNN was developed to calculate the deflection bowl parameters along with peak surface deflections from roughness, traffic, pavement age, pavement temperature, and climatic conditions. Over 26,000 data points covering various geographic locations were used to establish a global model (R2 = 82 % for the test data) to evaluate the structural integrity of asphalt pavement layers. It is envisioned that this study would assist roadway agencies in assessing the overall condition of asphalt pavements synergizing functional and structural characteristics.

Finite Element Model for Vibration Serviceability Evaluation of a Suspended Floor with and without Tuned Mass Dampers

This study aims to provide an accurate finite element (FE) modeling method for structural vibration serviceability evaluation of the suspended floor under human-induced excitation. The fundamental dynamic characteristics and human-induced vibration responses of a typical suspended floor were first measured via a series of field tests. Subsequently, the overall and local equivalent FE models of the suspended floor were respectively established, and their applicability was then verified by comparing the predicted dynamic characteristics and responses of the suspended floor with the corresponding field test results. Finally, passive tuned mass dampers (TMDs) were designed for vibration control of the suspended floor using the local equivalent FE model, and the applicability of the local FE model in assessing the vibration serviceability of the suspended floor with TMDs was further confirmed via pedestrian-induced vibration tests. Results demonstrate that the simplified local equivalent FE model proposed in this study can well replace the complicated overall FE model to evaluate the vibration serviceability of the suspended floor with and without TMDs.

An Intelligent Approach for Gas Reservoir Identification and Structural Evaluation by ANN and Viterbi Algorithm—A Case Study From the Xujiahe Formation, Western Sichuan Depression, China

Gas reservoir identification using seismic data has become a major focus of geophysical exploration. This study presents a gas reservoir identification and structural evaluation method using artificial neural networks (ANNs) and the Viterbi algorithm to improve processing efficiency and evaluate gas reservoir structural control. Initial identification was conducted using deep neural networks (DNNs). Composite seismic attributes sensitive to the multi-component seismic response characteristics of gas reservoirs were obtained. Subsequently, a model expansion dataset and network hyperparameter optimization strategy were employed to assess the optimal DNN model for ReLUactivation with nine hidden layers (3–5–7–7–7–9–9–11–11–11–1). The training model was run with the three composite attributes as input to predict the gas-bearing probability distribution. Considering the importance of evaluating geological structural characteristics, an automatic horizon tracking method using the Viterbi algorithm was proposed to evaluate the structural factors of gas reservoirs. Finally, the ANN-based gas reservoir identification results were comprehensively evaluated based on structural characteristics, thus, reducing the uncertainty, or multiple solutions, predicted by mathematical methods. This scheme was successfully applied to assess synthetic and real data, demonstrating the consistency between the predicted gas reservoir areas and true situation. The effective implementation of this scheme improves processing efficiency and provides a new way to shorten the exploration cycle of a gas reservoir.

Fatigue life and fatigue reliability assessment for long-span spatial structure based on long-term health monitoring data

Fatigue life and fatigue reliability assessment for long-span spatial structure based on long-term health monitoring data

Structural monitoring method for RC column with distributed self-sensing BFRP bars

Reinforced concrete (RC) columns may be damaged under earthquakes or wind loads, which will severely affect their bearing capacity. Current damage evaluation methods are mainly based on displacement measurement, which makes evaluating local structural damage difficult. Therefore, this study proposes an RC column structural monitoring and evaluation method based on a distributed self-sensing basalt fiber reinforced polymer (BFRP) bar with optical fiber sensors inside. First, the self-sensing BFRP bar is introduced, including the sensing principle, inner structure, and basic sensing performance. It is found that the strain sensing coefficenet of the proposed self-sensing BFRP bar presents only 2.2% difference from that of the bare optical fiber sensor, meaning the BFRP package take no negative effect on the strain sensitivity. Second, the analytical methods of curvature and displacement are established based on the strain distribution measurement, in which the influence of bond-slip on parameter calculations is mainly considered. Finally, the proposed method was well verified by the loading tests of one RC column with self-sensing BFRP bars. Among the results, the absolute displacement measurement error increase with the development of structure damage, which can be even up to several mm after the steel yielding. However, the relative displacement measurement error can be still controlled within 20% until the structure failure of the RC column. Considering the additional long-term performance of the proposed self-sensing BFRP bar, the proposed method is expected to implement long-term monitoring of RC columns.

Structural efficiency of block for aviation piston heavy fuel engine

PurposeHigh reliability and high power-to-weight ratio are the technical difficulties in the development of aviation piston heavy fuel engines. This paper aims to provide a design evaluation method of the aero piston engine block, which can help R&D personnel quickly evaluate the performance of engine block, including effective bearing capacity and fatigue deformation, save a lot of experimental time and shorten the R&D cycle.Design/methodology/approachIn this paper, structural efficiency is used to evaluate the reliability and durability of the engine block. Structural efficiency is a new evaluation method that lists its corresponding connotation according to different objects. In this paper, the function of the engine block in the engine is explained in detail, and three quantifiable connotations of the structural efficiency of the engine block are put forward. In the subsequent calculation, the calculation is carried out according to the three indexes, and the calculation results are used as the indexes to evaluate the performance of the engine block.FindingsThe structural efficiency evaluation method proposed in this paper can quickly and effectively evaluate the performance of the block from many aspects. Under the same boundary conditions, the two design schemes are simulated and analyzed, and the durability test is carried out. The analysis and experimental results show that Scheme 2 has good performance, which verifies the feasibility of the evaluation method.Originality/valueThis paper provides a method for rapid evaluation of engine block performance.

RC structures life-cycle probabilistic evaluation method considering mesoscopic material uncertainty with chloride ingress

Due to the attack of harmful environmental substances, the reinforcements in concrete can be corroded. The corrosion of reinforcements induces the concrete crack and the reduction in structural capacity. The complex durability deterioration at the material scale is commonly oversimplified in the structural analysis, and the influence of reinforcement corrosion distribution can hardly be evaluated in traditional methods. Benefitted from the accurate material model and efficient solution technologies, a structural life-cycle probabilistic evaluation method is proposed based on the material uncertainty influence. The computational framework consists of three steps. First, the simulation of chloride ingress in structural cross-section considering mesoscopic variation; second, the finite element analysis of structural response with modifying reinforcement corrosion states; third, the structural life-cycle performances are evaluated probabilistically with the trained Artificial Neural Network model. Focussed on the life-cycle hysteretic performance of the reinforced concrete column, the whole procedure is operated for illustration, and the time-dependent decreasing structural performance are investigated. Compared with widely used macroscopic methods, the model precision can be refined over 90%. By discussion effects of different measures to improve structural performance are studied, including increasing concrete strength and concrete cover. The results show that the thicker concrete cover can postpone the initial deterioration and significantly increase structural life-cycle performance probabilistically, and with the same designed action effect, the structural service life can be extended over 85% to reach same reliability.

A Few Issues on Application of Seismic Design Based on Elastic-Plastic Analysis to Piping Systems

This study presents a few issues when implementing seismic design of piping systems using elastic-plastic analysis. In the current seismic design standards for piping, structural evaluation is carried out based on elastic analysis using beam elements. There seems to be no case studies for examining the structural evaluation method when elastic-plastic analysis is applied in comparison with the current seismic design standards for piping. In this study, the structural evaluation method when elastic-plastic analysis was applied was examined with reference to the current seismic design standards for piping. First, the stress when the elastic-plastic analysis was performed and the stress when the stress coefficient of the current elastic analysis was applied were compared. Next, the strain limit when elastic-plastic analysis was performed was discussed.