bluuebunny/crossref_metadata_2025 huggingface dataset:
Equitable Prioritization of Bridge Rehabilitation Projects Using a Spatial Multi-Criteria Decision Support Framework
Authors: Mohamadiazar Nasim , Ebrahimian Ali , Azizinamini Atorod
Published: July 2024

Transportation infrastructure in the United States faces a significant challenge with more than 40% of bridges surpassing the 50-year mark and 25% requiring rehabilitation, repair, or total replacement. This aging infrastructure, compounded by budget constraints, presents a critical issue that necessitates the prioritization of bridge rehabilitation projects. While traditional prioritization has focused on structural and traffic conditions, the pressing need to address social equity and environmental justice (SEEJ) concerns highlights the importance of a new approach. To address this need, this study aims to incorporate SEEJ considerations into the process of prioritizing bridge rehabilitation projects. To do so, a spatial multi-criteria decision-making (MCDM) method was leveraged to integrate diverse criteria into a coherent bridge rehabilitation prioritization framework. This framework integrates spatial data, encompassing flood-related factors, social aspects, and environmental parameters, with datasets representing structural and traffic conditions of bridges. This amalgamation yields an integrated vulnerability map that assigns vulnerability levels (from very high to very low) to each bridge that can be used as a proxy for prioritization. The practicality of the framework is demonstrated through its application in Miami-Dade County, Florida. The results underscore the importance of SEEJ considerations in bridge rehabilitation to address vulnerabilities, especially within marginalized communities. The proposed framework is adjustable and leverages readily available data, rendering it applicable beyond the study area. The framework can be used as a practical tool by decision makers, such as state Departments of Transportation, to prioritize bridge rehabilitation projects equitably, enhance the resilience of critical infrastructure, and promote inclusive and sustainable communities.
Microcracking Considerations in Full-Depth Reclamation with Cement
Authors: Louw Stephanus Johannes Hofmeyr , Jones David , Harvey John , Hammack Joseph
Published: July 2024

Drying shrinkage cracks in pavements rehabilitated using full-depth recycling with cement can reflect through asphalt concrete overlays. The effect of shrinkage cracks on the fatigue life of pavements increases with increasing crack width because of the loss of load transfer across the cracks. Wide shrinkage cracks can also lead to pumping of the subgrade material, leading to faulting of the base, loss of support, and eventual deterioration of the stabilized layer. One method to mitigate drying shrinkage cracks is with microcracking. Microcracking creates a network of hairline cracks in the stabilized layer which serve to relieve initial stresses during early hydration of the cement, thereby limiting the wider and more severe block cracks typical of cement stabilized layers. The process involves applying several passes of a steel drum vibratory roller, at maximum vibration frequency and amplitude settings, over the stabilized layer within a set time window after construction. The effectiveness of microcracking was investigated through regular crack monitoring and deflection testing over a four-month period on a 37-cell test road at the University of California, Davis. The results showed that microcracking does not prevent the development of shrinkage cracks but, in conjunction with selecting a mix design seven-day strength between 2.0 and 4.1 MPa (300 and 600 pounds per square inch), it can mitigate its effects by creating additional, thinner, more closely spaced, shrinkage cracks that are unlikely to reflect through the asphalt concrete surfacing.
Use of Machine Learning for Automated Classification of Sand Type
Authors: Li Linzhu , Iskander Magued
Published: July 2024

This study demonstrates the feasibility of utilizing machine learning (ML) for routine identification of sand particles. Identifying different types of sand is necessary for various geotechnical exploration projects because understanding the specific sand type plays an important role in estimating the physical and mechanical properties of the soil. To accomplish this, dynamic image analysis was employed to generate a substantial volume of sand particle images. Individual size and shape descriptors were automatically extracted from each particle image. The analysis involved use of 40,000 binary particle images representing 20 different sand types, and a corresponding six size and four shape descriptors for each particle (400,000 parameters). Six ML models were trained and tested. The work demonstrates that using size and shape features the models efficiently identified up to 49% of individual sand particles. However, when clusters of particles were considered in conjunction with a voting algorithm, classification accuracy significantly improved to 90%. Among the ML models studied, neural networks performed the best, while decision tree exhibited the lowest accuracy. Finally, the use of size consistently outperformed shape as a classification parameter but combining size and shape parameters yielded superior results across all sands and classifiers. These findings suggest that ML holds much promise for automating sand classification using ordinary images.
Illegal Weigh Station Bypassing
Authors: Brown Mallory , Martin Andrew , Li Xiaobing , Leddy David , Walton Jennifer
Published: July 2024

This study was conducted to determine the extent of illegal weigh station bypassing in Kentucky, including the resulting safety and financial implications. Historical data (2017 to 2021) collected by Kentucky State Police–Commercial Vehicle Enforcement, observation data, and a state survey distributed to law enforcement officials across North America were used in tandem to provide evidence that illegal weigh station bypassing is indeed a problem that justifies swift, comprehensive action. Between 2017 and 2021, there were 2,616 charges for illegal weigh station bypassing in Kentucky. Drivers charged with illegal weigh station bypassing were also charged for an average of two additional violations. Site visits to permanent weigh stations along I-75 revealed that illegal weigh station bypassing was a persistent problem, even among preclearance (PrePass and Drivewyze) users. A survey was sent to law enforcement officials across North America to determine whether other jurisdictions were experiencing similar levels of noncompliance, as well as identifying which methods were being used to combat it. With a survey response rate of 56%, and 49% of respondents reporting a recent uptick in illegal weigh station bypasses, a nationwide problem was confirmed. Despite 70% of jurisdictions reporting enforcement efforts to curb illegal weigh station bypassing, it is clear that increased enforcement levels alone will not be sufficient. With safety and financial implications mounting across North America from illegal weigh station bypassing, novel approaches are warranted.
Machine Learning Methods for Geotechnical Site Characterization and Scour Assessment
Authors: Yousefpour Negin , Liu Zhongqiang , Zhao Chao
Published: July 2024

Reliable geotechnical site characterization and geohazard assessment are critical for bridge foundation design and management. This paper explores existing and emerging artificial intelligence-machine learning methods (AI-ML) transforming geotechnical site characterization and scour assessment for bridge foundation design and maintenance. The prevalent ML techniques applied for subsurface characterization are reviewed, and step-by-step methodologies for stratigraphy classification, borehole interpretation, geomaterial characterization, and ground modeling are provided. The ML techniques for maximum scour depth prediction are reviewed, and a simple ML methodology is proposed to provide a more reliable tool for scour depth estimation for implementation in practice. Also, a novel deep learning approach, with a detailed implementation description, is recommended for real-time scour monitoring and assessment of existing bridges. The challenges with database design and data processing for ML modeling, model optimization, training and validation, and uncertainty assessments are discussed, and innovative techniques for addressing them are reviewed.
Understanding Incident Effects on Subway Operations: Clustering Analysis of Severity Patterns
Authors: Abolfazli Mostafa , Trépanier Martin , Labbe Aurélie
Published: July 2024

Incidents pose challenges to the reliable operation of urban rail transit systems. Given the high frequency of subway services, even minor incidents can cause cascading delays across multiple trains. Understanding incident effects is crucial for improving response time and enabling efficient recovery strategies. This study uses operational records from the Montreal subway system to quantify the overall impact of incidents including the number of affected trains and total delay time. The proposed approach involves integrating operational records with incident data to identify the source of delays and subsequent knock-on effects. To recognize distinct propagation patterns among various incident types, K-means clustering is applied to categorize incidents into three clusters. Cluster 1 represents incidents with the lowest impacts, affecting only one direction of a subway line and imposing an average total delay time of 16 min. Cluster 2, which comprises most incidents, causing moderate operational impacts with an average total delay time of 52 min. Cluster 3 includes severe incidents, affecting an average of 26 trains and causing a total delay time of 273 min. Peak hour analysis indicates that morning and evening peak hours have the highest average number of affected trains, emphasizing the impact of peak hours on incident severity. Investigation into the causes of incidents highlights that the most frequent incidents fall into Cluster 2, implying moderate impacts on subway operations. This research provides valuable insights into subway incident management, laying the groundwork for further studies aimed at enhancing the performance of urban rail transit systems during service disruptions.
Application of Multiplicative Two-Stage Network Data Envelopment Analysis in Measuring and Improving the Efficiency of Container Ports in Southeast Asia
Authors: Nguyen Minh-Anh Thi , Tsai Feng-Ming
Published: July 2024

In response to the surge in container volumes, Southeast Asian nations have embarked on multiple port development projects. Considering the significant costs associated with port infrastructure, conducting a meticulous efficiency evaluation becomes imperative to determine the suitable direction for port development and guarantee the success of these investments. This study proposes a comprehensive framework using a multiplicative two-stage network data envelopment analysis model to investigate the efficiency of major container ports in Southeast Asia. It assesses how the technical efficiency of each stage within the port operation contributes to the overall technical efficiency of the port. Furthermore, the technical efficiency of each stage is measured based on two components: pure technical efficiency and scale efficiency. The key findings of the study can be summarized as follows. Firstly, most container ports in Southeast Asia exhibited relatively low levels of technical efficiency. Secondly, the underperformance was primarily caused by technical inefficiency in the building capacity stage, rather than the utilizing capacity stage. Thirdly, inadequate scale operation emerged as a significant issue for most ports. Based on the empirical results, the container ports are classified into four groups, and specific recommendations are provided for the development direction of each port group.
Real-Time Urban Traffic Monitoring Using Transit Buses as Probes
Authors: Jiang Shangkun , Sun Yuran , Wong Wai , Xu Yiming , Zhao Xilei
Published: July 2024

Real-time urban traffic monitoring is crucial for effective smart city management. Despite the increasing number of sensors collecting large-scale datasets in real time, challenges such as privacy concerns, high capital and maintenance costs, and limited coverage persist, impeding precise network traffic monitoring. General Transit Feed Specification (GTFS) Realtime data, an emerging real-time data source generated by public transit, exhibits high potential to monitor traffic given its public accessibility, low cost, and lack of privacy concerns. This study developed a new methodology leveraging GTFS Realtime data for citywide network sensing. Specifically, the proposed methodology uncovers the typical travel patterns of buses by isolating their operational events, involving boarding and alighting passengers at bus stops. Two algorithms, the segment-trip extraction algorithm and the segment speed estimation algorithm, were developed to implement the proposed methodology. The validation process used Bluetooth data collected in Gainesville, Florida, as the ground truth, while Google Traffic data served as a benchmark for comparison. Results indicate that the space mean speed estimated from GTFS Realtime data can better capture link speed trends and variations, similar to those observed in Bluetooth data. Furthermore, bus travel times derived from GTFS Realtime data demonstrated relatively high correlations with Bluetooth data and low prediction errors compared with estimates based on Google Traffic data. The proposed methodology and findings of this study can be directly used to complement and improve existing real-time traffic monitoring technologies.
Routing Optimization of Two-Echelon Two-Way Logistics in Rural Areas Based on E-Commerce Environment
Authors: Hong Wei , Du Chen , Xu Shuling , Pu Xujin
Published: July 2024

This is a study of the two-echelon two-way logistics vehicle routing problem in rural areas while accounting for government subsidies to alleviate the high distribution costs associated with “long transportation chain + low consumption density” in rural logistics. To address the issue, an improved adaptive ant colony optimization (IACO) algorithm was developed and simulations were run to validate it. The experimental findings demonstrate that, in comparison with the conventional adaptive ant colony optimization algorithm method, the IACO algorithm offers superior optimization capabilities. Finally, a case study was conducted in a rural area of China to demonstrate that the two-echelon two-way logistics network outperforms the current single-echelon logistics network by shortening the total driving distance and reducing distribution costs. This research can inform the optimization of rural logistics networks and provide a reference for the rural e-commerce logistics industry.
Post-Disaster Traffic Micro-Circulation System Design for Traffic Distribution Optimization
Authors: Gao Xueyi , Ci Yusheng , Zhang Lili , Wu Lina
Published: July 2024

Aiming at the problem of a substantial decrease in the traffic-carrying capacity of the road network caused by the breakage of the main roads after the disaster, this study constructs a bi-level programming model by the theory of traffic micro-circulation to alleviate the impact of disruptions. The upper model determines the roads constituting the traffic micro-circulation system and their traffic management measures, which maximizes the increase of traffic supply by using existing transport infrastructure; the lower model allocates traffic under the premise of the road geometry determined by the upper model; and the model solving algorithm is established by genetic algorithm. Finally, the road network of the New-Mart area in Daqing City, Heilongjiang Province, China, was taken as the research object for example analysis. The results showed that after the deployment of the traffic micro-circulation system, the average saturation of main roads was reduced from 0.99 to 0.75, the average saturation of the road network was reduced to 0.54, and the proposed method was able to maximize the operational efficiency of the road network after a disaster.
Household Change and Related Demographic and Social Indicators in Botswana During 1971–2011
Authors: Ntshebe Oleosi
Published: July 2024

This article examines household change and related demographic and social factors in Botswana during the last 40 years (1971–2011). The analysis uses data from five Botswana censuses and three nationally representative surveys: the 1988 Botswana Standard Demographic Health Survey (BSDHS), the 2000 Multiple Indicator Survey (MICS) and the 2007 Botswana Family Health Surveys (BFHS). Overall, the analysis affords a demographic and socio-economic perspective on the change in Tswana households, which is not generally available in census reports and other population survey analyses but is crucial to family and household policy.
Phospholipase A2 expression in prostate cancer as a biomarker of good prognosis: A comprehensive study in patients with long follow-up
Authors: Recuero Saulo da Cunha , Viana Nayara I , Reis Sabrina T , Mendes Keith T , Talib Leda L , Gattaz Wagner F , Guimarães Vanessa R , Silva Iran A , Pimenta Ruan C. P , Camargo Juliana A , Nahas Willian C , Srougi Miguel , Leite Katia R. M
Published: July 2024

Background:

Phospholipase A2 (PLA2) is a large family of enzymes involved in the inflammatory process that catalyzes the hydrolysis of membrane phospholipids, leading to the production of free fatty acids and lysophospholipids, starting the arachidonic acid cascade. Their expression has been related to the behavior of several cancers. Our objective is to search for PLA2 expression in prostate cancer (PCa) tissue that correlates with prognosis and survival.

Methods:

Using qRT-PCR, we analyzed the expression levels of PLA2G1B, PLA2G2A, PLA2G2D, PLA2G4A, PLA2G4B, PLA2G4C, PLA2G4D, PLA2G4E, PLA2G4F, PLA2G6, PLA2G7, PLA2G16, PNPLA1, and PNPLA2 in PCa tissue from 108 patients submitted to radical prostatectomy, followed by a mean time of 163 months.

Results:

All PLA2 was overexpressed in PCa compared to normal tissue. Interestingly, higher expression of some PLA2 was related to favorable prognostic factors: lower levels of PSA (PLA2G2A, PLA2G4D), lower rates of lymph node metastasis (PLA2G16 and PLA2G1B), and organ-confined disease (PLA2G4A). Most importantly, PLAG4B was independently related to longer disease-free survival.

Conclusion:

This is the first study exploring comprehensively the expression levels of PLA2 in PCa, showing that the higher expression of some PLA2 should be used as biomarkers of good prognosis and longer disease-free survival.
Prevalence of cutaneous manifestations and myositis-specific antibodies in COVID-19 patients and Anti-PL7 antibodies association with pulmonary radiological severity: A retrospective study
Authors: Oddenino Giorgio Alberto , Canepa Paola , Cozzani Emanuele , Gasparini Giulia , Garlaschi Alessandro , Roccatagliata Luca , Schiavetti Irene , Parodi Aurora
Published: July 2024

Background

Dermatomyositis (DM) is an idiopathic immune-mediated myopathy, and may involve many organs, including muscles, skin and lungs. Myositis-specific autoantibodies (MSAs) are a useful aid in diagnosis DM and identifying its clinical subtype. During the COVID-19 pandemic, several studies found clinical similarities regarding lung involvement in both COVID-19 and DM. Such similarities have prompted speculation of a common pathogenetic mechanism. Indeed, viral infections are well-known triggers of autoimmune diseases. This prompted us to investigate whether circulating MSAs could be markers of the severity of lung involvement and of clinical outcome in COVID-19 patients. Moreover, we investigated the presence of cutaneous signs of DM in COVID-19 patients.

Methods

We conducted a retrospective cohort study on 178 hospitalized patients affected by COVID-19. The diagnosis was confirmed by naso-pharyngeal swab positivity for SARS-CoV-2. The severity of lung involvement was assessed by assigning to each patient a radiological score ranging from 1 to 4, based on chest imaging (chest X-rays or CT scans). Serum samples were tested for MSAs.

Results

Anti-PL-7 antibodies were detected in 10.1% of patients and were found to be associated with an increased risk of severe pulmonary involvement ( p = 0.019) and a worse prognosis in COVID-19 patients. Cutaneous lesions were observed in 26.4% of patients. However, none were cutaneous manifestations of DM.

Conclusions

The detection of anti-PL7 antibodies might predict severe pulmonary involvement and a worse prognosis in COVID-19 patients.
Recommendations on the translation of academic texts in the social sciences and the humanities
Authors: Bielsa Esperança , Cussel Mattea , Raigal Aran Judith , Barranco Oriol , Bestué Carmen
Published: July 2024

These recommendations are addressed not only to translators, but to all users of translation, including authors and readers of academic texts, journal editors and publishers, as well as reviewers. They call attention to the translated nature of many works that are often viewed as originals, and through which English as the academic lingua franca is constantly produced and reproduced in a multilingual space. Rather than approaching translation as a hindrance, they seek to highlight its transformative potential and to call for more constructive approaches to the translation of academic texts. Academic translation, these recommendations maintain, relates to the particularities of the language of the social sciences and the humanities, as distinct from that of scientific and technical texts. Relying on a theory of translation as a procedure that involves specialized techniques for the rewriting of texts, they address the relationship between writing and translating, the collaboration between academic authors and translators, and relevant issues relating to the politics of translation in a highly unequal academic field.
The Urban Context of Rental Housing Development near Major U.S. Universities
Authors: Mawhorter Sarah L. , Ehlenz Meagan M.
Published: July 2024

Residential developers have found footholds in university-adjacent neighborhoods, though the extent of this trend is unclear. We examine rental construction near 168 major U.S. universities with neighborhood data covering 2000 to 2018. We find that more rental units were built near larger universities with growing enrollments and limited dormitory capacity. University-adjacent rental development varied widely across urban contexts, and was most common in low-mid-rent neighborhoods with similar precedents. More large-scale rental housing was built in medium-sized cities with higher housing prices yet slower rising rents. Findings suggest the importance of municipal and university roles in residential development, including local regulations and dormitory investments.
Evaluating the Diagnostic Performance of Nasal Methicillin-Resistant Staphylococcus aureus Polymerase Chain Reaction in Hospital-Acquired Pneumonia Within the Intensive Care Unit. A Retrospective Study
Authors: Alwakeel Mahmoud , Obeidat Mohammed , Nanah Abdelrahman , Abdeljaleel Fatima , Wang Xiaofeng , Fadell Francois
Published: July 2024

Background: The methicillin-resistant Staphylococcus aureus (MRSA) accounts for 20% to 40% of all hospital-acquired pneumonia (HAP) cases with mortality rates up to 55%. Prompt and accurate diagnosis is essential, especially in intensive care unit (ICU) patients. Nasal MRSA polymerase chain reaction (PCR) diagnostic utility evidence is conflicting in the literature for HAP due to a low number of HAP patients included in prior studies or due to the lack of high-yield gold standard cultures defined for comparisons. Methods: This was a retrospective cohort study conducted in a 65-bed medical ICU, and encompassing all adult patients admitted from January 2015 to March 2023 for HAP. Respiratory cultures included were those obtained by bronchoalveolar lavage or endotracheal suction within 7 days of nasal MRSA PCR testing. Results: The study included 412 patients; 56.8% were males and 65% were Whites. The mean age was 60.5 years. Most patients (82.5%) underwent MRSA-PCR before intubation, and the average time between MRSA-PCR and lower respiratory cultures was 2.15 days. The diagnostic performance of nasal MRSA PCR in diagnosing HAP in the ICU yielded a sensitivity (Sen) of 47.83%, specificity (Sp) of 92.29%, positive predictive value (PPV) of 26.83%, and negative predictive value (NPV) of 96.77%. For nonventilator HAP (nv-HAP) cases sensitivity was at 50%, specificity 92.83%, PPV 28.57%, and NPV at 97.00%. In ventilator-acquired pneumonia (VAP-HAP), the corresponding values were 42.86%, 90.91%, 23.08%, and 96.15%, respectively. Conclusion: The nasal MRSA PCR shows a high NPV and low false negative rate, suggesting it is a reliable tool for ruling out MRSA HAP in ICU patients. Care should be taken into account for disease prevalence and clinical context, as these factors may influence test performance. Further validation through prospective large-sample studies utilizing high-yield lower respiratory tract cultures is necessary to confirm our findings.
Repurposing Racial Modernism: Specters of Planning's Past, a Contested Present, and Alternative Planning Futures
Authors: Chavez-Norgaard Stefan
Published: July 2024

South African racial modernist planning was undemocratic, acontextual, and top-down, with enduring consequences. This article argues that repurposing built spaces marred by racial modernism constitutes a planning “next practice”: incrementally, repurposing suggests what forms of spatial transformation are possible. Synthesizing primary interviews, archival data, in-situ analyses of urban space, and secondary sources, the article traces how bureaucrats and residents repurpose built sites in Mahikeng/Mmabatho, South Africa, which experienced extreme racial-modernist planning as a receiving site of forced relocation and capital of the apartheid-era Bophuthatswana “Bantustan.” The inquiry reveals planning as dynamic and open-ended, subject to recontextualization and alternative planning futures.
Patterns and Consequences of Delayed Self Care Among Rural Medical Providers
Authors: Terry Danielle L. , Safian Gabrielle , Terry Christopher P.
Published: July 2024

Purpose

The purpose of this study was to (a) examine personal healthcare practices of rural medical providers by issue type (e.g., physical health, social health, or mental health), (b) identify perceived consequences of taking time off and (c) determine whether greater delay in self-care was associated with perceived stress and burnout.

Design

Electronic surveys were sent to 805 medical providers (response rate = 17.8%, n = 143).

Setting

The setting was a rural teaching hospital and affiliated community clinics.

Subjects

Participants included 143 rural medical providers.

Measures

The survey included demographic information, perceived personal health risk, and questions about delaying health care, and perceived consequences of receiving health care.

Results

Medical providers delayed mental health care needs significantly more than physical health needs, t131 = 5.13, P < .01, d = .38. Respondents believed that there would be significantly more retaliation against them for taking time off for psychosocial issues, t124 = −3.80, P < .001, d = .25. There was a significant negative association between burnout and physical health self-care (r = −.24, P < .01), psychosocial self-care (r = −.20, P = .01), and mental health self-care (r = −.23, P < .01).

Conclusions

Our study identified commonly reported consequences related to taking off work for care seeking behavior. Understanding perceived consequences can help guide health care organizations in dismantling these barriers. This study is limited by the generalizability of its sample.
Flight conflict detection of large fixed-wing UAV in joint airspace
Authors: Ma Xin , Li Zixuan , Yang Zhou , Lu Xikang , Zheng Linxin
Published: July 2024

To resolve the issue of cooperative operation between large fixed wing Unmanned Aerial Vehicle (UAV) and civil aviation manned transport aircraft, preprocessing of large fixed wing UAV flight data that oriented to spatial dimension will be carried out to further complete the mathematical description and sort out the characteristics of the flight data of the digital twins, analyze the track protection zone of flight program recommended by International Civil Aviation Organization (ICAO) and systematic errors such as collision risks, then develop a flight conflict detection method applied to cooperative operation in joint airspace and draw certain quantitative conclusion. According to the simulation experiments and calculation results, it is shown that the use of the multi-element composite strategy (MCS) can achieve the flight conflict assessment of the joint airspace cooperative operation, and according to the assessment results combined with the implementation environment of the flight mission, it can be concluded that the density of the airspace is within the range of the systematic error standard stipulated by the ICAO, so as to complete the quantitative assessment of the safety risk of the cooperative operation and the planning scheme of the joint airspace Preliminary formulation, to provide support for the development of intelligent logistics.
Numerical simulation of thermo-mechanical coupling in laser-MIG hybrid welding utilizing dual volume heat sources
Authors: Han Xing , Feng Lei , Li Chang , Sun Han
Published: July 2024

Laser-MIG hybrid welding is an energy-saving welding process. It is of great significance to quantitatively investigate the instantaneous evolution of temperature and stress in the process of hybrid welding to reveal the mechanism of hybrid welding and improve welding quality. Existing studies lack systematic analysis of temperature field and thermal stress field of laser-MIG hybrid welding of stainless steel, and there are relatively few literatures comparing traditional MIG welding and hybrid welding process. In this paper, the thermal mechanical coupling model of laser-MIG hybrid welding of SUS301L-HT stainless steel was established by numerical simulation. The temperature field, thermal stress field, and residual stress field distribution of the hybrid welding were quantitatively revealed, and compared with traditional MIG welding. The calculation results show that compared with the traditional single-heat source MIG welding, the center temperature of the laser-MIG hybrid welding pool is higher, and the peak temperature can reach 3386 K. Compared with the traditional MIG arc welding, the thermal stress distribution of laser-MIG hybrid welding is more uniform and the thermal stress value is lower at the same time. The distribution trend of residual stress in the two welding processes is similar. The overall residual stress in hybrid welding is relatively small, and the transverse residual stress and the thickness residual stress both have peak values in the heat affected zone. The research can provide theoretical reference and guidance for optimizing stainless steel hybrid welding process and improving welding quality and efficiency.
Concurrent predictions of tension, compression, and shear characteristics of epoxy using three-network viscoplastic model
Authors: Kumar Siddharth , Singh Sarthak S
Published: July 2024

Epoxy resin controls the mechanical behavior of fiber-reinforced epoxy composites, which are extensively deployed in the aerospace and automotive industries. For numerical simulations to accurately predict the mechanical deformations of these components under multi-axial loading, matrix characteristics must account for tension, compression, and shear loads at varying strain rates. The existing literature lacks a comprehensive approach to predicting the experimental outcomes across all three loading conditions in a polymer matrix simultaneously using a unified set of viscoelastic or viscoplastic model parameters. In this study, the Three-Network (TN) viscoplastic model was successfully applied to concurrently predict the tension, compression, and shear experimental data of an epoxy resin, published by Littel et al. ( Journal of Aerospace Engg., 2008). The elastic modulus, strain softening-hardening response after yield for tension-compression deformation, and post-yield stress saturation under shear deformation are all accurately predicted by the model at different rates of loading conditions. The predicted and simulated results matched well when the TN viscoplastic model predicted parameters were employed as material property in Abaqus (a commercial finite element software) to simulate the deformation modes. This integrated approach highlights the potential of the TN model in enabling precise predictions for epoxy-based composites, which is crucial for optimizing their performance and reliability in aerospace engineering.
Bending and linear dynamic response of nanoplates in thermal environment
Authors: Van Lieu Pham , Trong Hai Nguyen
Published: July 2024

The article combines the finite element method with the novel-type sinusoidal hyperbolic shear strain hypothesis to study the static bending response and dynamics of nanoplates subjected to simultaneous mechanical, thermal, and voltage loads. The plate equilibrium equation is developed from the concept of potential work, which takes into account the impact of the flexoelectricity effect. The formula for the electric field that is operating on the plate becomes more complicated when the new strain theory is used; nonetheless, its complexity adequately displays both the mechanical and electrical components, as well as the electromechanical components, that are acting on the nanoplate. The computational theory is also verified through comparison with previously published data. The article also investigates the influence of some material factors, temperature, and external voltage on displacement response and charge polarization of nanoplates in the case of subjecting to static and time-varying loads. The results demonstrate that the thermomechanical-electrical response of nanoplates is dependent on numerous factors, which serve as the foundation for the practical design and application of nanostructures.
A multi-objective coupling parameter hierarchical optimization framework for a novel dual-motor powertrain system of electric vehicle
Authors: Lin Cheng , Liu Huimin , Yu Xiao , Xie Peng
Published: July 2024

Collaborative optimization of the coupling parameters of powertrain is essential to improve the performance of electric vehicles. However, complex coupling relationships and multi-objective trade-offs bring challenges to traditional heuristic optimization algorithms, limiting the exploitation of system performance. To improve optimization accuracy and the performance of vehicles, a global parameter optimization framework for multi-power source systems is proposed. Specifically, the optimization framework consists of three layers, the middle and bottom layers respectively perform multi-disciplinary and multi-objective collaborative optimization of the coupling parameters to obtain a Pareto front formed by the optimal combination of parameters. Furthermore, the decision layer utilizes the Technique for Order Preference by Similarity to Ideal Solution to perform a comprehensive evaluation of the solution on the Pareto front to scientifically obtain the best solution and the weight coefficient range. The simulation results demonstrate that the optimized optimal solution improves dynamic performance by 15.77% while reducing operating costs by 7.37% compared to the initial parametric solution, resulting in a significant improvement in vehicle economy. Meanwhile, the parameter optimization design regularities of the dual-motor system are summarized.
Quantitative research on the tracked vehicle energy consumption characteristics based on the longitudinal-vertical coupling dynamics
Authors: Guo Zhiqiang , Liu Chunwang , Zhu Hongxiu , Luo Junlin , Wu Wei
Published: July 2024

In this paper, an energy computation method is proposed based on the longitudinal-vertical coupling tracked vehicle dynamic model to quantificationally study the energy generation and dissipation for tracked vehicles under off-road conditions. When the tracked vehicle drives on uneven road, the suspension damping components and the additional driving resistance caused by ground roughness consumes part of the driving power. The energy consumption distributions of the tracked vehicle under different speeds, different road conditions and different driving conditions are investigated and compared. The results indicate that a larger road roughness coefficient, a higher travelling speed and a greater driving force will make the proportions of energy consumed by the suspension dampers and the additional driving resistance to the total energy consumption larger. The influence of road conditions on the energy consumption distribution of the tracked vehicle takes precedence over the tracked vehicle speed and the effect of the driving force is internally due to speed changes.
Simulation analysis of quarter car active suspension control based on QBP-PID
Authors: Wu Yunshi , Su Donghai
Published: July 2024

In order to further improve the stability and comfort of automobile active suspension, a BP neural network controller based on Q-learning algorithm optimization (QBP-PID) is proposed. QBP-PID uses BP neural network to adjust the PID gain, introduces the optimal strategy of Q-learning to correct the weight momentum factor, and optimizes the key weights in the neural network, so that the controller has better learning ability and online correction ability. A quarter suspension simulation model with random road excitation as the system input is established in Simulink software. The root mean square of body acceleration and tire dynamic displacement are used as the evaluation indexes of active suspension performance. The simulation results show that compared with the traditional passive suspension, PID control suspension and BP-PID control suspension, the active suspension using QBP-PID control algorithm can significantly improve the driving stability and comfort of the vehicle.
An experimental investigation of single- and two-phase flow in copper and aluminum microchannel heat sinks
Authors: Meral Zeynep Küçükakça , Küçükoğlu Umut , Parlak Zekeriya , Parlak Nezaket
Published: July 2024

In this study, single- and two-phase flow and heat transfer characteristics in copper and aluminum heat sinks were investigated experimentally. Deionized water was used as the working fluid in the experiments. Two-phase flow tests were performed at low vapor qualities (∼0.1). Each heat sink has a square shape of 20 mm × 20 mm. Heat sinks have 15 parallel microchannels. The hydraulic diameters of the channels range from 400 to 500μm, and their aspect ratios range from 0.4 to 2.5. The effects of material and aspect ratio on two-phase flow were studied. Experimental Nu values for single-phase flow were found to vary with an increasing trend between 4.6 and 7.2 values. The data overlap with the data obtained from the Sieder-Tate correlation for Re > 280. For Re < 280, the difference reaches 25%. The pressure drop in two-phase flow is 2.5 times higher than that measured in single-phase flow. The heat transfer coefficients of two-phase flow decreased with increasing the degree of vapor quality and increased with increasing mass flow rate. Heat transfer coefficients were found to be higher for 2.5 aspect ratio than coolers with similar hydraulic diameters. Additionally, the heat transfer coefficients of the copper heatsink were higher than those of aluminum.
Effect of heat input on the mechanical and metallurgical aspects of double-pulse MIG welded IN 617
Authors: Singaravel Thayumanavan , Radhakrishnan Santhankrishnan , Thangaraju Deepan Bharathi Kannan
Published: July 2024

In this article, an attempt is made to analyze the influence of heat input in double-pulse metal inert gas (DP MIG) welding of Inconel 617 (IN 617). IN 617 plates were joined in the butt joint configuration with 1.2 mm diameter IN 617 filler wire. Three welding trials were conducted at different heat input, viz. 31.3, 37.1, and 41.5 J/mm. Weld quality was assessed using bead geometry, tensile strength, toughness, and hardness. The changes in mechanical properties were discussed using the optical microscope, scanning electron microscope with energy dispersion spectroscopy, and backscattered energy diffraction. Substantial changes were observed in the weld tensile strength for a small variation in heat input. Molybdenum segregation was observed in all the weld samples. At lower heat input, the tensile test was reduced by 31.62% compared with base metal. Similarly, for the medium and high heat input, the tensile strength was reduced by 25.13% and 49.59%, respectively. Weld had lower toughness compared with the base metal and no significant variation was observed in toughness to changes in heat input. Hardness of the weld at all three heat inputs was almost similar to base metal. Liquation cracks were seen in the partially melted zone. At higher heat input, the lack of sidewall fusion was observed along with liquation crack.
Treatment patterns and preferences of people living with HIV starting or switching antiretroviral therapy: Real-world evidence from Portugal
Authors: Pedro Liliana , Zagalo Alexandra , Tavares Raquel , Pacheco Patrícia , Oliveira Joaquim , Vaz Pinto Inês , Serrão Rosário , Tavares Sandra , Brito Paula , Maltez Fernando , Neves Isabel , Carvalho Alexandre , Teófilo Eugénio , Almeida Joana , Lains Inês
Published: July 2024

Background

There is a lack of up-to-date real-life evidence on antiretroviral therapy (ART) strategies among people living with HIV (PLWH) in Portugal. This study aimed to describe the treatment strategy used in PLWH either initiating or switching ART.

Methods

Non-interventional, cross-sectional, multicenter study carried out between December 2019 and October 2021 in Portugal.

Results

A total of 237 PLWH were included in this study, 171 of whom were ART-experienced and 66 were ART-naïve. The study showed that triple regimens were the most common ART strategy and integrase strand transfer inhibitors-based therapy was the most frequently used therapeutic class in both ART-naïve and ART-experienced PLWH. Nevertheless, about a third of PLWH who started a triple regimen transitioned to a dual regimen. Patient-reported outcomes revealed high HIV literacy and similar ART preferences in both groups.

Conclusions

This real-world study showed that triple regimens were the most widely used ART strategy, even after the European AIDS Clinical Society guidelines introduced the recommendation of a dual regimen for naïve patients. The cohorts of this study presented a high level of HIV literacy at the time of inclusion. Our findings highlighted that taking pills only once a day is considered a very important feature for most patients.
On the designing of robust dynamic observers for continuous-time systems in T-S fuzzy model with interval time-varying delays
Authors: Naami Ghali , Ouahi Mohamed , Rabhi Abdelhamid , Tadeo Fernando , Udris Dainius
Published: July 2024

Delay-dependent robust [Formula: see text] fuzzy dynamic observers (HFDOs) for continuous-time T-S fuzzy systems with interval time-varying delays, are studied here, considering the presence of exogenous disturbances. The proposed approach involves the creation of an augmented Lyapunov-Krasovskii functional through the utilization of an integral inequality based on the Wirtinger-based integral inequality and the extended reciprocally convex combination inequality. These techniques lead to delay-dependent conditions that are less conservative and that can be represented as a set of linear matrix inequalities, solvable using the YALMIP toolbox. Two detailed examples are presented at the end of the paper to illustrate the overall effectiveness of the proposed observer, which performs better than existing observers such as the [Formula: see text] fuzzy proportional observer (HFPO) and the [Formula: see text] fuzzy proportional-integral observer (HFPIO).
Robust finite frequency control for MRF damper-based semi-active suspension systems subject to time delay and hysteresis nonlinearity
Authors: Deng Mengqi , Kin Wong Pak , Gao Zhijiang , Ma Xinbo , Zhao Jing
Published: July 2024

The magnetorheological fluid (MRF) semi-active suspension (SAS) is a crucial system for the absorption and the dissipation of vibration energy. However, the hysteresis nonlinearity of the MRF actuator is difficult to tackle in the control design of the MRF-SAS system. A novel robust finite frequency control strategy based on a Taylor approximation is proposed in this work to improve the vibration suppression of the MRF-SAS system with hysteresis nonlinearity. First, a hyperbolic tangent model is introduced to represent the nonlinear dynamic characteristics of the MRF damper, and then the modified Taylor expansion is adopted to approximate the hyperbolic tangent model. Moreover, an online sequential extreme learning machine (ELM) is employed to construct the inverse model of the MRF damper. Finally, to trade off vehicle handling stability and ride comfort, the robust finite frequency controller is designed based on the linear matrix inequations (LMIs) with the consideration of the time delay, the control perturbation, and the actuator saturation. It can be seen from the simulation results that the proposed robust finite frequency controller is more effective in improving vibration suppression of the MRF-SAS system than the skyhook controller.
Retrospective analysis of carcinogenicity assessments within FDA-notified GRAS determinations
Authors: Rahmani Khatera , Wu Yen-Ching , Buck Neil R. , Lau Alexandria , Hanlon Paul R.
Published: July 2024

Frameworks have been developed to standardize the assessment of carcinogenic potential in the pharmaceutical and agrochemical industries, building upon decades of research. Carcinogenicity is also evaluated during the safety evaluation of food substances, using a comprehensive approach unique to each substance. To better understand these approaches, a retrospective assessment was conducted on the publicly available database of substances notified to the United States Food and Drug Administration (US FDA) as being Generally Recognized As Safe (GRAS). The data contained within these GRAS notifications (GRNs) were reviewed for the methods used to evaluate carcinogenic potential (genotoxicity studies, 2-year bioassays, other pre-clinical animal studies) to identify patterns that could provide an understanding of how this assessment has been conducted for different categories of food substances. While different approaches to the safety evaluation were required to adapt to the unique food substances, the data in all notifications supported the conclusion of safety. The evaluation of food substances for carcinogenic potential must consider all available data, including identifying the need for when more data must be generated to support an evaluation. Due to the complexity of substances used in food, ranging from defined chemical entities to minimally processed agricultural commodities to live microorganisms, the approach to conducting the safety evaluation of food substances must be able to adapt to the most relevant scientifically supported approach. This paper illustrates the data commonly used to support the safety of different types of food substances and proposes an approach familiar to other product sectors.