Weak Points Research Articles

Optimization and multiphysics analysis of high-performance lithium niobate modulators

Thin-film lithium niobate electro-optic modulators (TFLN EOMs) are widely utilized across various fields due to their exceptional performance. In this theoretical study, we optimized a TFLN EOM featuring a multimode interference coupler, cosine-curved waveguides, and a modulating arm straight waveguide structure. By tuning the etching depth, waveguide width, and geometric parameters of the traveling wave electrodes, we achieved a half-wave voltage-length product of 1.6V⋅cm and a 3 dB bandwidth of approximately 140 GHz. Additionally, we performed a multiphysics analysis to investigate the temperature characteristics of the modulator. The results indicate that increased temperature induces thermal-optic effects in the material, leading to changes in the waveguide’s refractive index and the optical beam phase, which results in increased insertion loss. Moreover, the stress generated by thermal expansion is concentrated in the modulator’s waveguide, representing a weak point that is prone to failure.

Temperature Distribution of Frozen Wall Formed by Irregular Hole Arrangement During In Situ Repair of Underground Shield Machine

In order to study the development law of the irregular hole freezing temperature field, combined with the shield solution project of the Nanjing Water Supply Corridor, the distribution characteristics and influencing factors of the irregular freezing temperature field of the river bottom shield machine are studied by numerical simulation. The following conclusions are obtained: (1) The extension length of the outer ring pipe is correlated approximately positively with the thickness and average temperature of the freezing wall at the bottom of the cup. The thickness increases by 0.25 m, and the average temperature decreases by 1.25 °C for every 1 m increase in the extension length. (2) The intersection time decreases logarithmically with the increase in the extension length of the outer ring tube. (3) As the ratio of the axial angle between the two adjacent tubes in the weak area of the outer ring tube becomes larger, the temperature of the weak point in the center of the two tubes increases approximately linearly. The midpoint temperature of the two tubes increases by 3.3 °C for every 1 increase in the angle coefficient. (4) With the increase in the opening angle of the inner ring hole, the thickness and average temperature change, respectively, at 150 d are not more than 0.15 m and 0.6 °C. The results show that under the irregular freezing form, the angle and length of the outer ring pipe have a great influence on the temperature field, and the angle of the inner ring pipe has little influence on the final distribution of the temperature field. The average temperature and the temperature distribution of the weak points show a trend of decreasing first and then increasing along the shield advancing direction, reaching a minimum near the cutterhead.

Interface Microstructure and Mechanical Properties of Nickel/Steel Bimetal Composite Pipe Fabricated by Explosive Welding

In this paper, the microstructure and mechanical properties at the interface of Incoloy825/X65 bimetallic composite pipe achieved by explosive welding were systematically studied. Results show that a periodic wavy bonding interface was formed between the Incoloy825 and X65 due to the jets caused by the high-impact stresses during explosive welding, which was beneficial for improving the bonding strength of the Incoloy825 and X65. Atomic diffusion and localized melting occurred near the interface during explosive welding. Some fine crystal grains were generated in the vicinity of the interface due to the strong plastic deformation and dynamic recrystallization, whereas some elongated grains growing in the perpendicular direction to the interface were found in the wider localized melted zone. Room temperature nanoindentation test showed that due to the existence of fine grains resulting from the recrystallization at the interface, the hardness of the interface was higher than that of the base metals. Voids and defects were prone to appearing in the vortex regions near the interface, where the weak point in the interface was located.

A novel FMECA method for CNC machine tools based on D-GRA and data envelopment analysis

Failure Modes, Effects, and Criticality Analysis (FMECA) is a commonly used method for analyzing system reliability. It is frequently applied in identifying weak points in the reliability of CNC machine tools. However, traditional FMECA has issues such as vague descriptions of risk factors, equal treatment of risk factors, and unclear directions for improving weak points. In response to the issue of vague descriptions of risk factors, this paper further expands severity (S) into machine hazard (M) and personal hazard (P), and subdivides detectability (D) into functional structural complexity (D1) and detection cost (D2). In addressing the issue of treating risk factors equally, this paper integrates Distance Analysis Method (DAM) and Grey Relational Analysis (GRA) to propose Distance-Grey Relational Analysis (D-GRA). Subsequently, based on the D-GRA method, the weights of each risk factor were determined by comprehensively considering expert system scores and actual economic loss indicators. In response to the issue of unclear improvement directions for weak points, this paper introduces the BCC model. It treats common failure modes of CNC machine tools as decision-making units within the BCC model, refines risk factors as input indicators, and evaluates the efficiency values of each decision-making unit based on various actual losses as output indicators. Through efficiency value analysis, it proposes improvement directions for weak points. Then, based on the weights of risk factors and the efficiency values of failure modes, a modified calculation method for the new Risk Priority Number (RPN) is proposed to amend the traditional RPN, This paper takes the electric spindle system of a certain machining center as an example, applies the proposed method to rank common failure modes with the new RPN, and compares it with other RPN calculation methods to verify the rationality of the proposed approach. Finally, it presents improvement directions for reliability enhancement.

Luspatercept in β‐thalassemia: Who and when. Strengths and weaknesses points of a real‐world evidence

Luspatercept in β‐thalassemia: Who and when. Strengths and weaknesses points of a real‐world evidence

Experimental and Statistical Investigations for Tensile Properties of Hemp Fibers

This study investigated the tensile behaviors of hemp fiber bundles and examined how properties including tensile strength and Young’s modulus vary with the bundle diameter. Hemp fibers were extracted, degummed, and separated into bundles of different diameters ranging from less than 50 μm to over 150 μm. Tensile tests were conducted on these fiber bundles using a rheometer-based tensile testing machine. The results showed that hemp fibers exhibited a tensile strength of 97.33 MPa and a Young’s modulus of 3.77 GPa at a 50% survival probability. However, the scale parameters for breaking stress and Young’s modulus were determined to be 620.57 MPa and 29.88 GPa, respectively. As the fiber bundle diameter increased, the tensile strength decreased significantly. This was attributed to the higher probability of defects and irregularities acting as weakness points in larger fiber bundles. In contrast, Young’s modulus (stiffness) increased with increasing bundle diameter, likely due to improved fiber–fiber interactions. To further understand the variability and reliability of the tensile properties, statistical models were developed. The Weibull distribution analysis was applied, revealing critical insights into the variability of diameter, stress at break, Young’s modulus, and strain at break. The Weibull parameters provided a comprehensive understanding of the fibers’ mechanical reliability. Additionally, the Griffith model was employed to predict the strength and Young’s modulus based on fiber diameters, supporting the observation that thinner fibers generally exhibited higher tensile strength due to fewer defects. Overall, this work highlights the importance of understanding structure–property relationships in natural fibers like hemp for optimizing their performance in composites.

Numerical and Analytical Study on the Punching Shear Capacity Prediction for Eccentrically Loaded Flat Slabs with Openings

The punching shear behavior of interior flat slab was examined in this study in the absence of shear reinforcement using numerical and analytical techniques. The effect of sensitive parameters was investigated and their influence was examined and reported including the opening existence and location, loading eccentricity, and slab height. The effect of the reinforcement ratio is neglected in most of the literature models and code provisions with the influence of loading eccentricity being addressed inappropriately. Therefore, this study adopted the nonlinear finite element analysis (NLFEA) method for the numerical part where the flat slab punching shear behavior was studied in detail. Results were compared in their behavior at both cracking and ultimate stages, absorbed energy, elastic and plastic stiffnesses, and general trend lines were provided. The effect of the reinforcement ratio was assessed indirectly with slabs of similar reinforcement area and different slab effective depths (65, 95, 125, and 155) mm where a 25 mm concrete cover was used. In addition, the NLFEA punching shear capacity results were compared with three international codes (American Concrete Institute (ACI318-119), EuroCode (EC2), and Model Code (MC2010)) to highlight their potential predictability and weakness points. It was found that the MC2010 has the most conservative prediction, followed by the EC2 and the ACI318-19 predictions. Therefore, two modification parameters were proposed for the ACI318-19 punching shear capacity calculation with R2 value of 0.98. The modified version of the ACI318-19 was validated using experimental data from the literature proving a high prediction capability.

Research on cracking characteristics and failure modes of semi-flexible pavement materials

Semi-flexible pavement (SFP) is designed for heavy traffic but its susceptibility to cracking hinders its development and application. This study aims to investigate the cracking characteristics and failure modes of SFP materials through macroscopic tests and image processing, thereby guiding anti-cracking technology. First, the effects of gradation and bitumen content on cracking process curves were analyzed using three-point bending tests across a wide temperature range. Second, the variations in maximum tensile strain, tensile strength, and fracture energy were comparatively examined. Finally, the morphology of specimens at crack initiation and after complete fracture was analyzed using image processing techniques to quantify the failure modes. The results indicate that the SFP material exhibits elastic development and brittle damage at the low temperature, and viscoelastic development and ductile damage at medium and the high temperature. At the low temperature, the changes in maximum tensile strain and fracture energy are consistent. The primary weak points at crack initiation include internal cement failure, cement-bitumen interface failure, and bitumen-aggregate interface failure. After complete fracture, internal cement damage and bitumen-bitumen/aggregate interface damage are dominant. To improve low-temperature cracking resistance of SFP, it is recommended to increase the maximum aggregate size, add fine aggregates, and increase the bitumen content. Additionally, enhancing the internal cohesion and external bonding properties of bitumen can mitigate the negative effects of increased bitumen consumption. This study provides guidance on designing the SFP material to enhance its crack resistance.

A study of comparison of perioperative complications in intraperitoneal onlay mesh technique vs extended view totally extraperitoneal ventral hernia repair

Background: Abdominal hernia occurs through the layers of the abdominal wall at a weak point. Laparoscopic ventral hernia repair (LVHR) is an established treatment for ventral hernias. This study was conducted in patients who underwent e-TEP and IPOM surgery for ventral hernia to characterize postoperative pain, recovery time, and quality of life. Predefined preoperative and peri-operative factors were examined for their potential impact. Methods: A prospective study on a total of 50 patients who underwent IPOM and e-TEP for ventral hernia was conducted, who fulfilled the inclusion criteria. Patients were randomized by simple random sampling technique and were divided into two groups of 25 each (Group A- e-TEP and Group B- IPOM). Data of both groups were compared and analysed for statistical significance using Chi square test and Student ‘t’ test. Results: The eTEP approach provides benefits compared to IPOM in terms of reduced hospital stay, earlier return to work and cost effective. However, eTEP is linked to complex learning process and in the end the decision of the surgery type should be made on the basis of specific patient’s conditions, surgeon’s expertise and availability of resources Conclusions: In study we found that both surgeries were comparable, with each having some benefits over the other.

Reporting and Grading of Complications in Urological Surgery: Current Trends and Future Perspectives.

There has been a growing need for enhancements in healthcare delivery, especially for the improvement of surgical outcomes. Therefore, implementing consistent reporting of complications enables the evaluation of data quality and facilitates its comparison. There are currently many available reporting and grading systems each with its own set of benefits and drawbacks. In this comprehensive review, we tried to present and assess each of them by demonstrating their criteria and their strong and weak points. To sum up, it seems that there is a need for developing a new reporting and categorization system for complications that are specific to urology.

Micro–Macro Coupling Study on the Mechanical Properties of Continuous Fiber-Reinforced Composites

As a key and weak point of continuous fiber-reinforced composites (CFRCs), the interface between the fiber and the matrix is vulnerable to failure under external loads, with its performance directly affecting the overall properties of CFRCs. Hence, a micro–macro coupling method that considered the microscopic properties of the interface was utilized to analyze and predict the mechanical properties of CFRCs more accurately. The microscopic mechanical parameters of the fiber–matrix interface, which were obtained using molecular dynamics, were transferred to the representative volume element (RVE). The stiffness matrix of the CFRC, required for the macroscopic finite element model, was then calculated using a unified periodic homogenization method based on the RVE and assigned to the finite element model for a macroscopic simulation. Nylon/continuous carbon fiber specimens were fabricated through additive manufacturing, with the tensile and bending strengths of the specimens obtained through tensile and three-point bending tests. The tensile strength of the experimental specimen was 200.1 MPa, while the result of the simulation containing the interface was 205.5 MPa, indicating a difference of less than 5% between the two. In contrast, the result of the simulation without an interface was 317.7 MPa, representing a high error of 58.7% compared with the experimental results. Moreover, the bending strength, Young’s modulus, and flexural modulus results with and without an interface showed the same trend as that for the tensile strength. This illustrates the effectiveness of the proposed micro–macro coupling method for analyzing and predicting the mechanical properties of CFRCs.

Microscopic analysis of low but stable perovskite solar cell device performance using electron spin resonance

Perovskite solar cells have attracted much attention as next-generation solar cells. However, a typical hole-transport material, spiro-OMeTAD, has associated difficulties including tedious synthesis and high cost. To overcome these shortcomings, an easily synthesized and low-cost hole-transport material has been developed: HND-2NOMe. Although HND-2NOMe has high local charge mobility because of the quasi-planar structure, its lower device performance is a weak point, the cause of which has not yet been clarified. Here, we analyse the source of the lower performance by clarifying the internal states from a microscopic viewpoint using electron spin resonance. We observe hole diffusion from perovskite to HND-2NOMe under dark conditions, indicating hole barrier formation at the perovskite/HND-2NOMe interface, leading to lower performance. Although such a barrier is formed, less hole accumulation for the HND-2NOMe-based cells under solar irradiation occurs, which is related to the stable performance. The sources of the lower but stable performance are crucially important for providing guidelines for improving the device performance.

Sisters But Not Twins: A Critical Appraisal of Long-Term Results in Breast Asymmetry Correction.

Breast asymmetry is a common disorder, which can lead to significant emotional distress. Despite this, there is currently no widely accepted approach for managing this prevalent condition. Due to the high dimorphism of the breast, despite a satisfactory result in the short-term post-op, the recurrence of asymmetry is one of the most common weak points of breast recontouring. The purpose of this paper is to investigate the long-lasting maintenance of breast symmetry in women who have undergone surgical correction of asymmetric breasts through mastopexy or reduction mammoplasty and to try to identify some specific elements to achieve more stable outcomes in the long term. A retrospective study was conducted on 1,984 breast surgical procedures carried out between 2002 and 2020 to evaluate patient satisfaction and the recurrence rate of asymmetry disorders. All the patients enrolled in this study were given a questionnaire to evaluate their satisfaction level. A retrospective iconographic-chart review was investigated by the same senior surgeon, who recorded the presence or the absence of recurring breast asymmetry. In total, 1984 patients were enrolled who respected the minimum standard of the study; 596 showed up at post-op follow-up longer than three years. Most of the patients showed great satisfaction with the results, even if several recurrences of asymmetry were reported. The recurrence of asymmetry is one of the most common weak points of breast asymmetry correction procedures due to the high dimorphism of the breasts. In order to fully assess the results of asymmetric breast correction, patients should be required to attend a post-op follow-up examination after a long time frame. Indeed, the strength of this paper lies in the focus on long-term postoperative follow-up. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Numerical analysis of vortex-induced vibration of deepwater drilling riser based on Van der Pol wake oscillator model

Coupled equations of the dynamic model and the Van der Pol wake oscillator model are solved by the central finite difference method for the deepwater drilling riser. The vortex-induced vibration (VIV) response and fatigue life of the riser are calculated and the model validation is performed by comparing with the published experimental and simulation results. The effects of the top tension, current flow velocity, flow velocity profile, internal flow velocity as well as the installation of buoyancy modules on the VIV are discussed. Dynamic response and fatigue life of the riser under In-Line (IL) and Cross-Flow (CF) VIV are preliminarily analyzed. The results show that the VIV of the riser has multiple modes and exhibits a mixed behavior of standing waves and traveling waves. With the increase of top tension and flow velocity profile coefficient, the order of the VIV dominant mode and the peak values of the root mean square (RMS) of VIV displacement decrease, and the fatigue life of the riser is extended. With the increase of current flow velocity, the order of the VIV dominant mode increases and the riser fatigue life decreases. The effect of internal flow velocity on the riser VIV is neglectable. The installation of buoyancy modules can improve the riser stress state and extend the fatigue life. Compared with the CF VIV model, the calculated minimum fatigue life of the riser is extended under the IL and CF coupled VIV model due to the decrease of bending moment and the changing position of fatigue weak point.

Forging the Resistive Republic: Social Capital, Institutional Stability, and Civic Virtue in Pluralist Democracies

Republicans too often take for granted features not easy to bring about in the absence of social capital. Lovett and Pettit (2009) consider that it is through collective political actions that citizens shed light on acts of domination. For Pettit (2012), civic vigilance is the only guarantee that “the government will be forced to remain responsive to popular inputs”. As Kimpell (2023) mentions, one of the weak points of republican theories remains the lack of an account of norm generation. I aim to show how this could occur in a way that does not constitute itself an arbitrary interference of the government in the people’s lives. The kind of generalized reciprocity which is of utmost importance for republicanism often depends on the presence of ties that connect different socio-economic groups within communities and, “where such interactions do not naturally occur, forums for interaction can be intentionally created and designed to encourage development of social capital” (Warner 2001). More specifically, I argue that such forums for interaction could be represented by polycentric systems. Furthermore, I argue that embracing polycentricity constitutes a non-dominating way in which we could promote the “resistive community” (Pettit 2012) required by republicanism. I consider that the empirical results extensively documented in the Institutional Analysis and Development framework are an appropriate starting point for designing novel republican policies and institutions that can function alongside sufficient levels of trust.

Measuring the Digital Maturity of Organisations in the People Care Sector

This study focuses on the organisations in the people care sector (OPCs), encompassing a broad spectrum of activities ranging from essential healthcare services to various aspects of daily living support. Sustainability in OPCs encompasses multiple dimensions aimed at ensuring the long-term viability, efficiency, and effectiveness of services provided to vulnerable populations. Given the critical role of digital technologies in enhancing the operational efficiency within such organisations and their sustainability, it becomes imperative to gauge their digital maturity levels. To establish a robust framework for assessing the digital maturity of OPCs, we identified 29 factors grouped into five clusters that encapsulate various dimensions of digital readiness that directly influence the sustainability of OPCs. We employed the SNAP methodology to ascertain the relative significance of these factors and clusters. Furthermore, each factor was articulated through the lens of digital maturity using the rubrics approach, offering a nuanced understanding of the OPCs’ digital readiness across four distinct levels. Experts from the people care sector, IT, and multi-criteria decision-making contributed invaluable input during the instrument’s development phase. Theoretical validation of the instrument involved focus group discussions with domain experts, while practical validation entailed applying the instrument to real-world case studies. The instrument enables OPCs to assess their digital maturity levels, providing valuable strategic planning and decision-making insights. Furthermore, the instrument can serve as a roadmap for identifying areas ripe for digital transformation and weak points, facilitating continuous improvement and future readiness. The quantification of the digital maturity of the OPC enables the OPCs to rank at the cluster maturity level and overall maturity level. Overall, this instrument represents a significant step towards enhancing digital maturity assessment within the OPC sector, contributing to its evolution and adaptation in the digital age, and enabling the OPCs’ sustainability.

Laser welding of dissimilar TiAl/Ti6-Al-4V materials: Effects of rapid in-situ laser pre-heating on microstructure and mechanical properties of the welding joint

TiAl alloy has broad application prospects in the aerospace field. In practical working environments, connecting with other materials is considered an important means of fully utilizing their excellent properties. This study employed a laser in-situ pre-scanning method to preheat the weld seam, achieving the connection between TiAl alloy and Ti-6Al-4V. On this basis, the microstructural evolution of the fusion zone (FZ), fusion line (FL), and heat-affected zone (HAZ) of the welded joint was analyzed in detail. By comparing with traditional welding processes, the effects of laser in-situ preheating on the microstructure and properties of the welded joints were studied. The results showed that the FZ area consists of α2 and martensitic α-Ti, while the FL on the TiAl side features a transition layer of β/B2 phases, providing plasticity and toughness to the welded joint. The in-situ scanning method reduced the cracks generated during welding, resulting in a more uniform distribution of the transition layer. The obtained FZ exhibited higher microhardness. The room temperature tensile strength of the welded joint reached 650 MPa. As the temperature increased, at 400 °C, the tensile strength and elongation reached 571 MPa and 3 %, respectively, significantly higher than the 450 MPa and 1.5 % achieved by conventional welding at the same temperature. When the temperature further increased to 500 °C and 600 °C, Ti-6Al-4V experienced significant softening, becoming the weak point of the welded joint.

Analysis and optimization of the dynamic response characteristics of aircraft cargo rack

In order to effectively achieve the optimization design of the aircraft cargo rack, based on finite element modal simulation, the structure was redesigned and analyzed using two schemes of surrogate model size optimization and topology optimization, ensuring the strength requirements while improving the natural frequency and reducing the weight. According to the modal shape of vibration, additional bridge structures were added at the weak points to improve the dynamic stiffness of the structure. According to the optimization design requirements, the response surface function was constructed, and the particle swarm optimization algorithm was applied in the size optimization and surrogate model solution. A multi-objective optimization model was established for flexibility and low-order natural frequencies, and topology optimization was carried out in HyperWorks. The structural dynamic modification of the topology optimization model was performed using the modal strain energy analysis method. The research results show that both optimization methods can achieve good lightweight design. The static performance of the optimized structure is stable, and the overall modal frequency is improved.

Этногенез чувашей в трудах Н.И. Воробьева: особенности трактовки

The article examines the contribution of Professor N.I. Vorobyev to the scientific study of complex aspects of the ethnogenesis of the Chuvash people. The scientist is rightfully considered one of the prominent researchers of the problem of the origin of the Chuvash. Being one of the leaders and authors of the first volume of the collective monograph “The Chuvash. Ethnographic research. Part One” (1956), N.I. Vorobyev outlined in it his so-called "autochthonous theory" of the ethnogenesis of the Chuvash, as a people based on Finno-Ugric, but with the Turkic Bulgarian language. The article highlights the scientist's not always unambiguous views on the origin of the Chuvash, as set out by him in publications of 1930, 1950, 1953. It is noted that while many scientists at the beginning of scientific research adhered to the concept of the Finno-Ugric origin of the Chuvash, and subsequently took the position of N.I. Ashmarin, N.I. Vorobyev initially rather inclined to the Bulgarian theory, and only later became an autochthoniste. It is pointed out that one of the weak points in the scientist's interpretation of the issues of ethnogenesis was the ignoring of the factor of their Bulgarian-type language. For N.I. Vorobyev, the main basis for judgments about the origin of the Chuvash was the material and partly spiritual culture, which had a lot in common with the Mari. The article also points to the fact that the scientist did not pay attention to the factor of pagan religion in the ethnic history of the Chuvash. At the same time, it should be noted that in search of the origins of the Chuvash people, he quite widely attracted materials from famous archaeological sites of the Chuvash region. Special attention is paid in the article to the coverage of critical assessments of N.I. Vorobyev’s views by Chuvash historians V.F. Kakhovsky and V.D. Dimitriev.

Recent advancement of immunotherapy targeting lung cancer

As one of the leading cause of deaths in all types of cancer, lung cancer has attracted public attention more than decades. Many chemotherapy and physical surgery therapies have been investigated and applied to lung cancer patients to increase the overall survival rate. As a more recently emerging therapy, immunotherapy is keep advancing in recent years and has achieved great success to complement the traditional therapys weak point and even become the first line treatment against certain types of non-small cell lung cancer (NSCLC). The safety and overall survival improvement of immunotherapy drugs has been tested through multiple cycle of clinical trials, validating their potential for lung cancer treatment. Several clinical trials study the application of immunotherapy singly or in combination with chemotherapy has been established to target lung cancer many years ago. Here, this review will introduce the three most common immunotherapies against lung cancer, and both summarize their application and discuss their recent advancement based on multiple ongoing or finished clinical trials.