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An essential greenhouse gas effect mitigation technology is carbon capture, utilization and storage, with carbon dioxide (CO 2 ) injection into underground geological formations as a core of carbon sequestration. Developing a robust 3D static model of the formation of interest for CO 2 storage is paramount to deduce its facies changes and petrophysical properties. This study investigates a depleted oilfield reservoir within the Bredasdorp Basin, offshore South Africa. It is a sandstone reservoir with effective porosity mean of 13.92% and dominant permeability values of 100–560 mD (1 mD = 9.869233 × 10 –16 m 2 ). The petrophysical properties are facies controlled, as the southwestern area with siltstone and shale facies has reduced porosity and permeability. The volume of shale model shows that the reservoir is composed of clean sands, and water saturation is 10–90%, hence suitable for CO 2 storage based on petrophysical characteristics. Static storage capacity of the reservoir as virgin aquifer and virgin oilfield estimates sequestration of 0.71 Mt (million tons) and 1.62 Mt of CO 2 , respectively. Sensitivity studies showed reservoir depletion at bubble point pressure increased storage capacity more than twice the depletion at initial reservoir pressure. Reservoir pressure below bubble point with the presence of gas cap also increased storage capacity markedly.

Middle Miocene reservoirs in the southern part of the Gulf of Suez province are characterized by geometrical uncertainties due to their structural settings, lateral facies change, different lithologies, and diverse reservoir quality. Therefore, in this study, detailed 3D geo-static models were constructed by integrating multiple datasets, including 2D seismic sections and digital well-logs. The 3D models were constructed for the Belayim Formation (Hammam Faraun Member), Kareem Formation (Markha Member), and Rudies Formation (Upper Rudies Member) with detailed structuration, zonation, and layering for Amal Field in the southern Gulf of Suez province to assess the hydrocarbon potential, calculate accurate reserves, recommend development and exploration plans, and propose locations for future drilling. The resultant structural model exhibited a compartmentalized area of major and minor normal faults trending NW–SE, forming structurally high potential hydrocarbon trapping locations in the study area. The petrophysical models indicated the good potentiality of Hammam Faraun as a reservoir with porosity values of 15–23%, increasing towards the central part of the area, volume of shale ( V sh ) of 21–31%, water saturation ( S w ) of 34–49%, and sand thickness increasing toward the northeastern part of the area. The Markha Member was also interpreted as a good reservoir, with porosity values of 15–22%, increasing towards the southeastern part of the area, V sh of 13–29%, S w of 16–38%, and sandy facies accumulating in the central horst block. Upper Rudies exhibits good reservoir properties with porosity values of 16–23%, V sh of 29–37%, S w of 35–40%, and good sandy facies in the central horst block of the area. The study results showed hydrocarbon potential in the central horst block of the study area for the Middle Miocene multi-reservoirs.

This study aims to determine the profile of the Mathematical Visual Static Model Problem Solving Ability. This study applies a qualitative approach by involving 8th-grade students at SMPN 1 Ajangale, who are selected from five different prototype groups and are based on students’ equations or mistakes in solving visual static model problems. Research subjects were selected during the data collection process from visual static model tests and interviews. The results showed that in completing the visual static model test, namely the first subject: overall good problem solving in knowledge skills, logical thinking, and mathematical logic, but did not have mathematical visualization and mathematical representation; for the second subject: mathematical representation, but lacks the ability of mathematical knowledge, logical thinking, mathematical understanding, visualization, and problem solving; for the third subject: mathematical knowledge skills, mathematical representation, mathematical understanding, problem solving, logical thinking, and mathematical visualization; for the fourth subject: logical thinking, but does not have mathematical understanding, mathematical knowledge skills, problem solving, mathematical representation, and mathematical visualization; and for the five subjects: logical thinking and mathematical representation, but lack of knowledge of mathematics, problem solving, mathematical understanding, and mathematical visualization.

In this paper, a quasi-static model of the resonant power converter with inverter, LLC circuit, and diode rectifier is obtained, which is a linear mathematical model derived from the analysis of quasi-steady-state processes of the substitution circuit for constant values of input and output signals. The quasi-static model is determined on the basis of the dynamic model of the resonant converter for infinite time, which made it possible to obtain analytical expressions of static characteristics based on transient functions. As a result of calculations based on the quasi-static model, the family of static characteristics of the resonant converter, which is replaced by the structure with equivalent voltage generators and a passive part of the circuit, is obtained. The passive part contains the resonant circuit, the voltage transformer, and some parasitic parameters of the transformer and other circuit elements. Equivalent voltage generators replace the voltage inverter with the power source and the rectifier with the load. Thus, the switched power circuit of the resonant converter is replaced by the non-switched circuit with voltage generators and the passive multipole. The input values of the substitution circuit are the voltages of equivalent generators, and their currents are the output values. Quasi-steady-state processes are represented as a set of stationary functions consisting of stationary transient functions. Stationary functions are the sum of individual transient functions that repeat from period to period of the operating frequency. To determine the transient functions according to the finite value theorem of the z-image, we use the transfer functions obtained from the discrete dynamic model of the resonant converter. The algorithm for switching power valves is taken into account when formulating the steady-state current formula of the output equivalent generator, at the intervals of non-zero voltage of which the average load current is determined by integrating the steady-state current. Comparison of the calculated static characteristics with the experimental characteristics confirmed the correctness of the theoretical results. References 24, figures 6, table 1.

Magnetorheological damper (MRD) has been successfully applied to vehicle suspension systems as an intelligent core component. Most conventional MRDs have closed rectangle-shaped magnetic circuits, resulting in a short effective working length and negligible damping force. To address the above issues, a novel full-channel effective MRD with trapezoidal magnetic rings (FEMRD_TMR) is proposed. The trapezoidal magnetic ring can shunt the magnetic circuit, distributing it evenly along the damping channel and increasing the effective working length. Additionally, which has the same variation trend as the magnetic flux through it, makes the magnetic induction intensity distribution more uniform to reduce the magnetic saturation problem. Theoretically analyzing the damping characteristics of the FEMRD_TMR, a quasi-static model is developed to forecast the output damping force. The structural design of MRD is challenging since conventional quasi-static models rely on the yield stress of magnetorheological fluid (MRF) to reflect the rheological property, which cannot be directly observed and is challenging to calculate. The Takagi–Sugeno (T–S) fuzzy neural network and a unique magnetic circuit computation are offered as a novel quasi-static modeling approach to address the issue. The MRF’s yield stress is linearized into magnetic induction intensity functions by the T–S fuzzy neural network and then converted into the MRD’s structural size by the special magnetic circuit calculation. Therefore, the proposed quasi-static model can directly reflect the relationship between the damping force and structure size, simplifying MRD’s structure design. The novel quasi-static model is shown to be more straightforward and understandable than the conventional Bingham quasi-static model and to have approximately accurate damping force prediction when compared to experimental data.

Addressing the scientific problem that the profile modification design of tapered roller bearings primarily focuses on contact stress and fatigue life while neglecting its impact on wear evolution, this paper, based on Hertzian contact theory and the Archard wear theory, and considering centrifugal force, gyroscopic effect, and the complex contact state between rollers and raceways, constructed a comprehensive analysis framework integrating a quasi-static model for profiled rollers and a wear depth calculation model. This framework is novel in that it systematically couples roller profile modification parameters with raceway wear evolution under both pure axial and combined radial–axial loads. The validity and effectiveness of the proposed model were verified by comparing the results of the quasi-static model with load distribution data from existing literature and through measurements conducted on a specially designed bearing wear test platform. The main findings are as follows: (1) When the logarithmic modification parameter f1 increases from 0.7 μm to 3.6 μm, the maximum wear depth of the inner raceway increases by 133% under pure axial load and 144% under combined load, while that of the outer raceway increases by 142% under pure axial load and expands from 0.1–0.2 μm to 0.23–0.52 μm under combined load. (2) Combined load induces significant asymmetric wear on the outer raceway, and the difference between the two wear peaks increases from 0.13 μm to 0.35 μm as f1 rises from 0.7 μm to 3.6 μm. (3) The wear peak shifts toward the midpoint of the roller generatrix with increasing modification amount. These results provide important guidance for the wear-oriented optimization design of tapered roller bearings.

•Dynamic transmission models of infectious disease capture the herd immunity effects of vaccination.•We compared dynamic and static models of maternal acellular pertussis (aP) immunization built with Brazilian data.•At infant vaccine coverage < 90–95%, both models estimate that maternal immunization is cost-effective.•Only the dynamic model shows that maternal immunization is not cost-effective at infant coverage > 90–95%.•The background effect of routine infant vaccination is critical to the cost-effectiveness of maternal aP immunization. This paper compares cost-effectiveness results from two models of maternal immunization to prevent pertussis in infants in Brazil, one static, one dynamic, to explore when static models are adequate for public health decisions and when the extra effort required by dynamic models is worthwhile. We defined two scenarios to explore key differences between static and dynamic models, herd immunity and time horizon. Scenario 1 evaluates the incremental cost/DALY of maternal acellular pertussis (aP) immunization as routine infant vaccination coverage ranges from low/moderate up to, and above, the threshold at which herd immunity begins to eliminate pertussis. Scenario 2 compares cost-effectiveness estimates over the models’ different time horizons. Maternal vaccine prices of $9.55/dose (base case) and $1/dose were evaluated. The dynamic model shows that maternal immunization could be cost-saving as well as life-saving at low levels of infant vaccination coverage. When infant coverage reaches the threshold range (90–95%), it is expensive: the dynamic model estimates that maternal immunization costs $2 million/DALY at infant coverage > 95% and maternal vaccine price of $9.55/dose; at $1/dose, cost/DALY is $200,000. By contrast, the static model estimates costs/DALY only modestly higher at high than at low infant coverage. When the models’ estimates over their different time horizons are compared at infant coverage < 90–95%, their projections fall in the same range. Static models may serve to explore an intervention’s cost-effectiveness against infectious disease: the direction and principal drivers of change were the same in both models. When, however, an intervention too small to have significant herd immunity effects itself, such as maternal aP immunization, takes place against a background of vaccination in the rest of the population, a dynamic model is crucial to accurate estimates of cost-effectiveness. This finding is particularly important in the context of widely varying routine infant vaccination rates globally. Clinical Trial registry name and registration number: Not applicable.

We consider a well-known quasi-static model for the shape of a liquid droplet. The solution can be described in terms of time-evolving domains in R^n . We give an example to show that convexity of the domain can be instantaneously broken.

A comprehensive quasi-static model of the tapered roller bearing with the modified roller element is established. Based on the slicing method, the wear depth models of both roller element and raceway are derived. The influences of roller element modification on the wear depth distribution characteristics of both roller element and raceway under different load conditions are investigated. The contact pressure distribution between roller element and raceway before and after wear are compared and analyzed. The results indicate that the modification of roller element has a significant effect on bearing wear. The smaller the modification amount, the lower the peak wear depth, and the peak wear position is closer to the end of the roller elements. Wear has a weak impact on the contact force between the roller element and the raceway, but leads to the increase of the peak contact pressure.

PurposeSoft grippers have safer and more adaptable human–machine and environment–machine interactions than rigid grippers. However, most soft grippers with single gripping postures have a limited gripping range. Therefore, this paper aims to design a soft gripper with variable gripping posture to enhance the gripping adaptability.Design/methodology/approachThis paper proposes a novel soft gripper consisting of a conversion mechanism and four spring-reinforced soft pneumatic actuators (SSPAs) as soft fingers. By adjusting the conversion mechanism, four gripping postures can be achieved to grip objects of different shapes, sizes and weights. Furthermore, a quasi-static model is established to predict the bending deformation of the finger. Finally, the bending angle of the finger is measured to validate the accuracy of the quasi-static model. The gripping force and gripping adaptability are tested to explore the gripping performance of the gripper.FindingsThrough experiments, the results have shown that the quasi-static model can accurately predict the deformation of the finger; the gripper has the most significant gripping force under the parallel posture, and the gripping adaptability of the gripper is highly enhanced by converting the four gripping postures.Originality/valueBy increasing the gripping posture, a novel soft gripper with enhanced gripping adaptability is proposed to enlarge the gripping range of the soft gripper with a single posture. Furthermore, a quasi-static model is established to analyze the deformation of SSPA.