Specific Design Research Articles

Technology roadmap toward the completion of whole-brain architecture with BRA-driven development

The development of brain-morphic software holds significant promise for creating artificial general intelligence that exhibits high affinity and interpretability for humans and also offers substantial benefits for medical applications. To facilitate this, creating Brain Reference Architecture (BRA) data, serving as a design specification for brain-morphic software is imperative. BRA-driven development, which utilizes Brain Information Flow (BIF) diagrams based on mesoscale brain anatomy and Hypothetical Component Diagrams (HCD) for corresponding computational functionalities, has been proposed to address this need. This methodology formalizes identifying possible functional structures by leveraging existing, albeit insufficient, neuroscientific knowledge. However, applying this methodology across the entire brain, thereby creating a Whole Brain Reference Architecture (WBRA), represents a significant research and development challenge due to its scale and complexity. Technology roadmaps have been introduced as a strategic tool to guide discussion, management, and distribution of resources within such expansive research and development activities. These roadmaps proposed a manual, anatomically based approach to incrementally construct BIF and HCD, thereby systematically expanding brain organ coverage towards achieving a complete WBRA. Large Language Model (LLM) technologies have introduced a paradigm shift, substantially automating the BRA-driven development process. This is largely due to the BRA data being structured around the brain’s anatomy and described in natural language, which aligns well with the capabilities of LLMs for supporting and automating the construction and verification processes. In this paper, we propose a novel technology roadmap to largely automate the creation of WBRA, leveraging neuroscientific insights. This roadmap includes 12 activities for automating BIF construction, notably extracting anatomical structures from scholarly articles. Furthermore, it details 11 activities aimed at enhancing the integration of Hypothetical Component Diagrams (HCD) into the WBRA, focusing on automating checks for functional consistency. This roadmap aims to establish a cost-effective and efficient design process for WBRA, ensuring the availability of brain-morphic software design specifications that are continually validated against the latest neuroscientific knowledge.

Comprehensive guidelines for appropriate statistical analysis methods in research.

The selection of statistical analysis methods in research is a critical and nuanced task that requires a scientific and rational approach. Aligning the chosen method with the specifics of the research design and hypothesis is paramount, as it can significantly impact the reliability and quality of the research outcomes. This study explores a comprehensive guideline for systematically choosing appropriate statistical analysis methods, with a particular focus on the statistical hypothesis testing stage and categorization of variables. By providing a detailed examination of these aspects, this study aims to provide researchers with a solid foundation for informed methodological decision making. Moving beyond theoretical considerations, this study delves into the practical realm by examining the null and alternative hypotheses tailored to specific statistical methods of analysis. The dynamic relationship between these hypotheses and statistical methods is thoroughly explored, and a carefully crafted flowchart for selecting the statistical analysis method is proposed. Based on the flowchart, we examined whether exemplary research papers appropriately used statistical methods that align with the variables chosen and hypotheses built for the research. This iterative process ensures the adaptability and relevance of this flowchart across diverse research contexts, contributing to both theoretical insights and tangible tools for methodological decision-making. This study emphasizes the importance of a scientific and rational approach for the selection of statistical analysis methods. By providing comprehensive guidelines, insights into the null and alternative hypotheses, and a practical flowchart, this study aims to empower researchers and enhance the overall quality and reliability of scientific studies.

Rutting prediction model of asphalt pavement based on RIOHTrack full-scale ring road

The research and prediction of rutting mechanism of asphalt pavement has always been the main difficult problem for road designers all over the world, and scholars have done a lot of research on how to prevent and control rutting of asphalt pavement. Based on the measured loading data of 80 million axis times of Beijing RIOHTrack full-scale ring road, rutting evolution of asphalt pavement with various structure types is studied in this paper and proposes the Kou&Cao rutting prediction model for the first time. Compared with other mature explicit rutting prediction models, this model has the characteristics of high prediction accuracy, strong robustness. At the same time, the model can provide a basis for predicting the inflection point of rutting evolution on asphalt pavement. The research results of this model are effective, which completes the effective analysis of the rutting evolution and development law of asphalt pavement, and provides an important reference for the future road design specification research and road construction.

An experimental study on web-bearing resistance of cold-formed steel sigma-shaped sections with web holes under interior-two-flange loading case

Cold-formed steel (CFS) sigma-shaped sections used as flooring joists and bearers are commonly fabricated with web holes to accommodate building services. These sections featuring web stiffeners and curved lips exhibit lower web-bearing resistance than traditional lipped channel sections. However, the web-bearing resistance of CFS sigma-shaped sections with web holes has not been thoroughly investigated. To address this gap, a detailed experimental investigation was conducted, testing 29 CFS sigma-shaped sections with web holes under an interior-two-flange (ITF) loading case. For comparison, specimens without web holes were also tested. Variables such as hole diameter ratio, hole location, bearing length, and flange condition were examined. A finite element (FE) model was developed and validated against the test results. The results indicated that the web-bearing resistance for specimens with web holes was reduced by 24.0% on average. To assess the accuracy of existing design specifications, the test results were compared against the design strengths predicted by the American Iron and Steel Institute (AISI) (2016), Australian and New Zealand Standards (AS/NZS) (2018), European Standard (EC3) (2006), and Uzzaman et al. (2012). The comparison revealed that the design strength predicted by Uzzaman et al. (2012) agreed well with the test results.

Current Feedback Operation Amplifier Based on Floating Passive and Active Inductors in Filter Applications

This paper proposes using current feedback operation amplifiers (CFOAs) as an active filter in creating floating passive and active inductance simulators is a versatile and efficient solution for circuit design. CFOAs are popular for their high slew rate and wide bandwidth which makes them ideal candidates for applications demanding rapid response time alongside high frequencies. It is possible to customize these simulated inductances for different design specifics by changing certain external resistor values. The circuit comprises a trio of CFOAs, an earthed capacitor and three resistors, thus making it quite simple to put into practice at a cheap price. Experiments and LTSPICE simulations have been conducted to examine the performance of the circuit, and closely confirmed theoretical expectations. In other words, this confirms the trustworthiness and preciseness of the introduced floating active inductance simulator. Voltage-mode band-stop filtering is one real-world scenario where this circuit is used. This indicates that our proposed technique can have more applications than one in circuit design. This is further proof that our idea can be used in other circuits as well. In conclusion, using CFOAs in active filters for building a grounded passive active inductance simulator is a solid and effective answer to circuit designers. This makes it an appealing choice for numerous applications because of its simplicity in designing the network as well as its high performance and customizability. Circuit design and application can be greatly improved if more study is done in this field.

COMPUTATIONAL EXPERIMENTS WHEN STUDYING MATERIALS PROPERTIES INFLUENCED BY "MIXTURE" FACTORS

Short information on computational materials science is given, with the methodology of material properties fields, in composition and process coordinates, as the part of it and as the background of the study presented in this paper. One of the main means of the methodology is random scanning the whole and local fields. These tools were developed and used to solve many problems in materials science related to the properties defined by mutually independent factors. The purpose of the study presented in this paper has been to develop the tool for random scanning the fields of properties effected by "mixtures" of q components, linearly related portions of components in rangers from 0 to 1, with their sum equal to 1. In these cases, the factors domain (or subregion of it) presents the simplex. The special designs of experiments to get reduced polynomials describing the fields in simplex coordinates are used. Two procedures for generating any number of uniformly distributed points on the simplex have been developed. These points define the virtual mixtures simulated in computational experiments. The procedures were tested by scanning the fields of two rheological characteristics of lime suspension filled with "short", “medium", and "long" cellulose fibers. Experimental-statistical models in the form of reduced polynomials for effective viscosity at shear rate equal to1 s-1 and for the rate of destruction of liquid structure (parameters of power-law model of flow, K = η1 and m) obtained in previous study are used to determine the levels of these characteristic for each of simulated mixture. Computational experiments were carried out, in which the fields of η1 and m in whole simplex domain and in some of its zones were scanned, allowing the generalizing indices of the fields and different correlations between η1 and m in different zones of mixture triangle to be estimated. The developed tools, the procedures of generating random points, which would define the simulated compositions of the "mixtures", make significant contribution to the progress of the methodology of recipe-technological fields of properties and to computational materials science.

디자인이 연구개발 성과에 미치는 영향 및 성공 사례 분석

The Technology Readiness Level (TRL), which is a research and development stage, is an indicator of the maturity of technology and is used to judge the progress of research and technology. As the TRL stage increases, the development is completed and the level of commercialization is nearing completion. During this process, design intervention is acting as an essential element in commercialization and technology transfer, unlike in the past. In particular, the definition of design concepts and detailed design elements must be made at the prototyping stage of TRL stage 3, which is very advantageous for future technology commercialization. Accordingly, we analyzed the impact and success factors of design by reviewing major domestic and international cases that achieved results through design in various research and development fields (6T) and research purposes. In addition, we investigated the contribution of design through interviews with experts in the field of advanced industrial technology (IT, ET, etc.) using the Good Design evaluation index. In particular, we specified the role of design applicable to each TRL stage based on the design process and presented specific methods such as the definition of design specifications. In conclusion, we have once again confirmed that recognizing the need for designers' active participation in R&D projects and establishing a convergence process centered on commercialization through design convergence are very important factors in creating R&D results.

Evaluation of Minimum Web Reinforcement Requirements for Slender and Non-Slender Beams

Prescriptive shear requirements in the U.S. from the American Concrete Institute (ACI) 318 (2019), the American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) Bridge Design Specifications (2020), and the fédération international du béton Model Code ( fib MC) (2010) include a minimum web reinforcement requirement. In general, slender beams require a minimum area of web reinforcement equal to 0.08% of the cross-section, while non-slender beams require up to 0.30%, or roughly three times more than the slender beam requirement. This investigation aims to evaluate the discrepancy between these requirements in relation to the strength and serviceability behavior of experimental test data. This is carried out through an analysis of existing and peer-reviewed databases. The results show that the minimum web reinforcement needed to ensure shear strength is consistent with code requirements for slender beams, but not non-slender beams. The minimum web reinforcement needed to restrain crack widths is consistent with code requirements for non-slender beams, but not slender beams. Thus, the prescriptive web reinforcement requirements for slender and non-slender beams do not appear to be derived from the same criteria. The requirement for slender beams is derived based on these members achieving their predicted strength, while the requirement for non-slender beams is derived based on the width of in-service cracks.

STRUCTURAL DESIGN AND ANALYSIS OF A 20-STORY MIXED-USE HIGH-RISE RESIDENTIAL AND COMMERCIAL BUILDING IN DHAKA: SEISMIC AND WIND LOAD CONSIDERATIONS

This study, conducted in the Department of Civil Engineering at Stamford University Bangladesh, focuses on the structural design and analysis of a 20-story mixed-use high-rise building in Dhaka, accommodating both residential and commercial functions. The objective of the study is to gain insights into the design and analysis of an intermediate moment-resisting frame that addresses the specific challenges posed by seismic and wind loads in a dense urban environment. A commercial building, defined as a structure primarily dedicated to business activities, requires specialized design considerations that extend beyond residential construction, including the need for larger beams, increased floor space, and accommodation for various commercial functions. In high-density urban areas, like Dhaka, the design of multi-story commercial buildings, such as shopping malls and office complexes, presents additional challenges related to space constraints, vertical shopping preferences, and the high cost of land. The study emphasizes the importance of creating a structural design that balances rentable space, aesthetics, cost, safety, and comfort, while addressing the lateral forces caused by wind and seismic activity. This analysis aims to assist engineers and architects in meeting the growing demand for multifunctional high-rise structures, ensuring both safety and functionality in the face of complex environmental and structural factors.

Characterization of internal defects in cylindrical components using laser ultrasonic method with a modified SAFT algorithm

The health monitoring of cylindrical elements is particularly important for the safe operation of industrial production, because cylinders bear a lot of support and transmission work. Normal non-destructive evaluation techniques need special designs to suit high curvature surfaces of cylinders. Laser ultrasonic (LU) method can provide a remote and non-destructive inspection solution to solid cylinders due to its flexible adaptability to complex structures and strong penetration depth. However, constrained by the common problems of optical detection systems, the detected ultrasonic signals will suffer low signal-to-noise ratio and bad resolution from poor sample surface quality. Thus, a modified synthetic aperture focusing technique (SAFT) optimized for cylindrical components is proposed to improve the detectability of LU on small and buried defects. Mode conversion wave signals obtained by multiple separate excitations are used in SAFT imaging for the reconstruction of the defects under surface profile correction. To reduce the influence of incident waves such as direct surface acoustic wave, besides common difference method, adjacent wave subtraction algorithm based on cross-correlation is used for signal preprocessing, suppressing the incident waves and exaggerating the mode conversion waves. In numerical simulation, internal defects with diameters from 0.6 to 0.2 mm with various buried depths are visualized and accurately located via the optimized SAFT algorithm using mode conversion waves. For validation, a circumferential scanning system is established in LU experiment and internal defects from 0.8 to 0.4 mm in diameter inside solid cylinders are successfully detected with precise location. The results elucidate the reliability of characterizing the location of small internal buried defects in solid cylinder structures through LU-SAFT imaging.

Critical current density of high-temperature superconducting ceramics BSCCO Bi-2223

In the paper the results of the study on the synthesis of high-temperature superconducting ceramics of nomi- nal composition Bi1.6Pb0.4Sr2Ca2Cu3Oy by various methods were presented based on amorphous phases using glass-ceramic technology and solid-phase method. For comparison, amorphous phases were obtained in two ways. In the first case, a heating furnace of a special design was developed to obtain an amorphous phase, which provides melting without using a crucible. The heating of the initial samples for melting is carried out due to the combined effect of the convection heat flux and the radiation of heating elements, which consists of the IR region of the spectrum at a melting temperature in the spectral range of 1300–1350 nm. In the se- cond case, melting is carried out under the influence of broadband optical radiation, including UV, visible and IR spectral regions. The production of glassy precursors is carried out by draining the melt onto a quenching device in the form of a propeller made of stainless steel. Studies of the formation rate of the superconducting high-temperature phase Bi-2223 were carried out in the same temperature conditions at 848–850 °C with in- termediate grinding every 24 hours and the study of the phase composition by X-ray diffraction method. Studies showed that the glass phase-based method ensures the completeness of the formation of the high- temperature phase Bi-2223 and the rate of its formation is significantly higher than by the solid-phase method (2.5–3 times). Studies of the critical density of the transport current have shown that the current value is 7.05×103 mA/cm2, (measured by the criterion of 1 µV/cm), which is significantly higher compared to other methods.

Photoresponsive conductive polymer network based on azobenzene bridging crosslinked polycarbazole for boosting solar thermal storage

Azobenzene is one of the most extensively researched multifunctional chromophores and azobenzene including materials has a wide variety of applications due to their photoisomerization behavior. In this study, electroactive and light-harvesting carbazole and photoresponsive azobenzene units have been combined with a special macromolecular design. In this design the azo groups can be effectively isomerized in solid state, and free-standing films can be obtained by the electrochemical method. Thermal characterizations of both monomer and polymer have been performed and isomerization kinetics and solar-thermal properties have been investigated. The half-life at 60 °C and the gravimetric energy storage density of polymer was calculated as 103 min and 179.9 j g−1, respectively. Cross-linked polycarbazole structure causes dramatically increased solar thermal storage and half-life compared to respective monomer and brought unexpected mechanical and solvatochromic properties.

Python-based numerical study on bolted joints between Fe-SMA and steel plates for structural reinforcements

In order to rehabilitate the performance of deteriorated steel structures, the active prestressed reinforcement employing new intelligent material, Iron-based shape memory alloy (Fe-SMA), has received extensive attentions. To reveal the mechanical properties of bolted joints between Fe-SMA and steel plates, a parametric method to establish finite element model via secondary development of ABAQUS based on Python scripts was proposed. It greatly reduces modelling costs and improves modeling efficiency. Besides, the proposed numerical models were verified against the experimental results by failure mode, final deformation, load-displacement characteristics, ultimate load-bearing capacity and initial stiffness. It is demonstrated that the numerical simulation results are in good agreement with the experimental results. What is more, a parametric study on thickness and geometry of steel plates, as well as the end distance, edge distance and thickness of Fe-SMA plate was conducted to verify the applicability of current leading specifications for steel structures. It is evident from the results that the thickness of Fe-SMA should be controlled to prevent failure of parent steel structures. Furthermore, similar to steel plates, the thickness of Fe-SMA plate can be considered linear and the failure of bolt can be avoided, as described in Chinese code GB 50017–2017 and Eurocode 3 Part 1–8. However, the minimum allowable edge distance in Chinese code GB 50017–2017 and the ultimate load-bearing capacity calculated by Eurocode 3 Part 1–8 is conservative for bolted joints between Fe-SMA and steel plates. Hence, it is urgent to formulate design specifications for this kind of bolted joints for the scientific and economical application of Fe-SMA in structural active reinforcements.

Risk stratification scheme based on the TNM staging system for dogs with oral malignant melanoma centered on clinicopathologic presentation.

Oral malignant melanoma (OMM) is the most common malignant oral neoplasm in dogs. Tumor recurrence, progression, and regional and distant metastasis remain major obstacles despite advanced therapy. Tumor size has been a consistent, key independent prognostic factor; however, other clinical and histopathologic features impact prognosis and likely influence optimal treatment strategies. Adoption of a risk stratification scheme for canine OMM that stratifies groups of dogs on defined clinicopathologic features may improve reproducible and comparable studies by improving homogeneity within groups of dogs. Moreover, it would aid in the generation of multidisciplinary prospective studies that seek to define optimal treatment paradigms based on defined clinicopathologic features. To build a platform upon which to develop a risk stratification scheme, we performed a systematic review of clinicopathologic features of OMM, with particular attention to levels of evidence of published research and the quantitative prognostic effect of clinicopathologic features. Tumor size and presence of bone lysis were repeatable features with the highest level of evidence for prognostic effects on survival. Overall, with strict inclusion criteria for paper review, the levels of evidence in support of other, previously proposed risk factors were low. Factors contributing to the challenge of defining clear prognostic features including inconsistencies in staging and reporting of prognostic variables, incomplete clinical outcome data, inhomogeneous treatment, and absence of randomized controlled studies. To overcome this in the future, we propose a risk stratification scheme that expands the TNM system to incorporate specific designations that highlight possible prognostic variables. The ability to capture key data simply from an expanded TNM description will aid in future efforts to form strong conclusions regarding prognostic variables and their influence (or lack thereof) on therapeutic decision-making and outcomes.

The Design of the Dummy Arm: A Verification Tool for Arm Exoskeleton Development.

Motorised arm supports for individuals with severe arm muscle weakness require precise compensation for arm weight and elevated passive joint impedance (e.g., joint stiffness as a result of muscle atrophy and fibrosis). Estimating these parameters in vivo, along with the arm's centre of mass, is challenging, and human evaluations of assistance can be subjective. To address this, a dummy arm was designed to replicate the human arm's anthropometrics, degrees of freedom, adjustable segment masses, and passive elbow joint impedance (eJimp). This study presents the design, anthropometrics, and verification of the dummy arm. It successfully mimics the human arm's range of motion, mass, and centre of mass. The dummy arm also demonstrates the ability to replicate various eJimp torque-angle profiles. Additionally, it allows for the tuning of the segment masses, centres of mass, and eJimp to match a representative desired target population. This simple, cost-effective tool has proven valuable for the development and verification of the Duchenne ARm ORthosis (DAROR), a motorised arm support, or 'exoskeleton'. This study includes recommendations for practical applications and provides insights into optimising design specifications based on the final design. It supplements the CAD design, enhancing the dummy arm's application for future arm-assistive devices.

Multicriteria selection practices in public tender evaluation process: the case of Sri Lanka

PurposeAwarding contracts based solely on the lowest price is unsuitable for every project. Consequently, most procurement systems in developed countries have progressed to the multicriteria selection practices (MSPs) for tender evaluation. MSPs consider a range of quality measures, such as completion time, life cycle cost, functional characteristics, environmental impact and innovation, alongside bid price. This study examines the prevailing MSPs in Sri Lankan public tender evaluations to enhance the effectiveness of the local tender evaluation process.Design/methodology/approachA desk study approach was employed to collect bidding documents, resulting in the identification of 66 documents. A systematic screening process was then applied to identify those bidding documents that incorporated MSPs. Subsequently, content analysis was conducted to determine the common features of the functions used in MSPs.FindingsThe study identified six primary functions related to MSPs incorporated in the bidding documents to procure building and substation projects. Three functions follow the price-to-quality method, while the remaining three follow the quality-to-price method. Among these identified functions, four functions employ objective evaluation criteria, such as thickness, capacity and operational loss. The other two functions utilize subjective evaluation criteria, such as the project’s design and technical specifications. Contract awarding will be based on either the highest score or the lowest bid, depending on the function type.Originality/valueThis study’s originality lies in exploring MSPs in the Sri Lankan public tender evaluation process and in disclosing their characteristics to promote the MSPs in Sri Lanka and developing countries.

Evaluation of the Implementation Status of the Nepal Rural Road Standards (NRRS) Concerning Geometrical Parameters: A Case Study of Morang District of Nepal

Maintaining the effectiveness of the transportation system is essential to economic growth. Poor road upgrading methods in many developing nations, however, are making it impossible for traffic to flow freely. Nepal developed the Nepal Rural Road Standards (NRRS) of 2055, District Transportation Master Plan (DTMP), and Municipality Transportation Master Plan (MTMP) to regulate the construction of rural road infrastructure. These guidelines provide guidelines for rural road planning, design, building, and maintenance, among other aspects. However, each geometric design has certain features, and parameter requirements depending on the region and location to be applied. This study aims to compare the geometrical features of the rural roads that have been built with the Nepal Rural Road Standards (NRRS) 2055, second revision (2071). Using a random sampling approach, six rural roads in the Morang district were selected for the data collection. To gather geometrical data, field observations and measurements were made at random chainages. This study evaluates various geometric parameters using linear and angular field measurements. Mapping conducted via smart road software ensures road geometry compliance, including aspects such as curve radius, shoulder width, gradient, sight distance, carriageway, and additional widening. The findings demonstrate that strict adherence to established standards substantially enhances road safety. Based on the results of the field observation, the geometric elements have been built according to design specifications, except for the additional widening at shoulder width and horizontal.

Long-term operational characteristics of subway source heat pump system under various tunnel internal heat source intensities

In recent years, subway systems have effectively alleviated urban traffic congestions. However, thermal pollution of underground spaces is a prevailing problem, which poses a serious threat to the safe and efficient operation of subways. The subway source heat pump system (SSHPS), equipped with a front-end tunnel lining heat exchanger, is an effective solution to tackle the aforementioned problem. However, the design methodology and operational strategy of the system is not yet established, which necessitates an analysis of its long-term operational characteristics. In this study, an SSHPS simulation model was developed using the TRNSYS simulation tool based on a demonstration project and the model was subsequently validated against measured data. The validated model was used to evaluate the long-term performance and operational characteristics of the subway system under various internal heat source intensities ranging from 0 W/m to 240 W/m. The simulation results showed that the tunnel air temperature steadily increased as the internal heat source intensity increased. When the internal heat source was 0 W/m, the average annual decrease in tunnel air temperature was 0.11 °C. However, the average annual tunnel air temperature did not fall below the minimum subway design specification temperature of 5 °C at any point in time. When the internal heat source was 120, 180, and 240 W/m, the tunnel air temperature exceeded the maximum temperature of 40 °C stipulated in subway design guidelines on multiple occasions. As the internal heat source intensity increased, the performance of both the heat pump unit and SSHPS progressively decreased during the cooling season and gradually increased during the heating season. The runtime of the heat pump unit gradually decreased from 92.72 % to 77.57 % during the cooling season, whereas it increased from 46.92 % to 89.41 % during the heating season. The heat pump unit exhibited an average energy efficiency ratio (EER) of 5.07, 4.95, 4.87, 4.80 and 4.76 whereas the SSHPS demonstrated an average EER of 3.04, 3.01, 3.00, 2.99 and 2.98. Throughout its operational years, the SSHPS consistently maintained stable and cyclically high performance. However, the system did not fully meet the specified cooling and heating loads under all operational conditions, indicating that there was a source–load mismatch issue within the system. Hence, it is recommended to incorporate auxiliary cold and heat sources, thereby establishing a composite heating and cooling system based on subway source heat pump technology, with the aim of enhancing the reliability of energy supply for the system. This study can serve as a valuable reference for formulating high-efficiency and energy-saving operational strategies for SSHPSs.

Class I Recalls of Cardiovascular Devices Between 2013 and 2022 : A Cross-Sectional Analysis.

Cardiovascular devices account for one third of all Class I recalls, the U.S. Food and Drug Administration's (FDA) most severe designation, indicating a reasonable probability of "serious adverse health consequences or death." Understanding recalls and their causes is important for patient safety. To characterize Class I recalls of cardiovascular devices and the clinical evidence supporting authorization. In this cross-sectional study, cardiovascular device recalls from 1 January 2013 through 31 December 2022 were identified using the FDA's annual log. Information about devices was extracted from publicly available FDA decision summaries. The FDA Medical Device Recalls database. Cardiovascular devices with Class I recalls. Recalls were characterized by their causes and scope. Devices were characterized by their regulatory history (product code, special designations) and clinical evidence (premarket testing, postmarket surveillance). Clinical studies were analyzed for quality, including end point selection (clinical vs. surrogate, use of composites). From 2013 to 2022, there were 137 Class I recall events affecting 157 unique cardiovascular devices, of which 112 (71.3%) were moderate-risk 510(k) devices and 45 (28.7%) were high-risk premarket approval (PMA) devices. Recalls affected a median of 7649 units (IQR, 953 to 28 446) and were most commonly attributed to device design (43 [31.4%]). Forty-two (26.8%) devices had multiple Class I recalls. Thirty (19.1%) devices underwent premarket clinical testing (7 [6.2%] 510(k) devices, 17 [85.0%] PMA devices, and 6 [24.0%] PMA supplement devices). Most studies used surrogate (27 [79.4%]) and composite (24 [70.6%]) measures as primary end points. Twenty-two (48.9%) PMA devices had required postapproval studies, with 14 reporting delays. No 510(k) devices were subject to postmarket surveillance. Details about clinical testing may be missing from FDA summaries. Cardiovascular devices with Class I recalls were infrequently subjected to premarket or postmarket testing, with recalls affecting thousands of patients annually. None.

A triplexer chip with cascaded butterfly multimode interference couplers by femtosecond laser microprocessing

A triplexer chip utilizing three cascaded butterfly multimode interference (MMI) couplers to output three optical signals from their respective ports is proposed. The chip consists of a borosilicate glass substrate, a JA photoresist core layer, and an RZJ photoresist cladding. The beam propagation method (BPM) is used to design and optimize the chip. The femtosecond laser processing is investigated, and the chip is processed with a laser power of 1.6 mW and an ablation speed of 4 mm/s. Tests show that the chip meets the design specifications with a low insertion loss of 4.34 dB, an extinction ratio of more than 15 dB, a crosstalk of less than −15 dB, and a 3 dB bandwidth up to 76.8 nm.