DSpace community: 機械與機電工程學系暨研究所

Development of the Bidirectional Full-Bridge CLLC Converter for Electric Vehicles

title: Development of the Bidirectional Full-Bridge CLLC Converter for Electric Vehicles abstract: This dissertation proposes a novel bidirectional full-bridge CLLC converter that is suitable for electric vehicle applications in the power grid system. The converter has bidirectional energy transfer capabilities, allowing for energy to be transferred from the high-voltage side to the low-voltage side and vice versa. In both modes, all switches exhibit soft-switching characteristics, which effectively reduce switching losses on both the high-voltage and low-voltage side power switches. Additionally, this converter has distinct resonant frequencies that extend the load range for zero-voltage switching (ZVS) and zero-current switching (ZCS), thereby enabling the converter to achieve improved efficiency under light-to-halfload conditions. This dissertation implements a prototype of a 2 kW-rated power converter that utilizes the Texas Instruments digital signal processor TMS320F28335 as the control platform. With its fast computation capability and flexible control planning, the converter achieves bidirectional energy transfer between high and low voltages. Through experiments, it has been verified that the efficiency is significantly improved under light-to-half-load conditions.

數位相移條紋投影量測系統之設計與實現

title: 數位相移條紋投影量測系統之設計與實現 abstract: 本研究建立完整的數位相移條紋投影量測系統來進行物體的三維曲面量測，在演算技術部分，本研究使用多步相位移技術、三種波形條紋、品質導引路徑相位展開技術及參考平面扣除法等。硬體部分，本研究設計了兩套系統，第一套稱為多角度三維複雜曲面量測系統，第二套稱為微米級形貌量測系統。多角度三維複雜曲面量測系統使用DLP投影機投射條紋結構光影像，再藉由CCD相機擷取變形的條紋結構光影像，並利用電控轉盤來控制CCD相機的量測角度，以觀察多步相位移在不同量測角度對物體三維曲面量測的影響。微米級形貌量測系統整合DLP投影機、光學鏡組、立體顯微鏡及CCD相機將條紋結構光縮小並用以量測微米級三維形貌。由實驗結果可知，在量測三維複雜曲面時，七步相位移在量測角度20°可得最佳量測結果，量測直徑50 mm滾珠螺桿之真圓度為0.05mm。在量測特定形狀時，餘弦波條紋對於直徑1 cm內凹半圓形待測物的量測誤差最小為1.27%，方形波條紋對於寬度3 cm長方形待測物的量測誤差最小為5.02%，三角波條紋對於邊長1 cm正三角形待測物的量測誤差最小為10.18%。在量測微米尺寸之形貌時，量測光纖解析度可達3 μm，與共軛焦顯微鏡量測結果比較，本量測系統精度高、架構簡單且操作容易。本系統可應用於生產線上之三維形貌檢測，對於自動化光學檢測領域有相當之助益。

Design of a General Type BSSO Fixation Plate Integrating Topology and Parameter Optimization for Various Severity Levels of Hemifacial Microsomia

title: Design of a General Type BSSO Fixation Plate Integrating Topology and Parameter Optimization for Various Severity Levels of Hemifacial Microsomia

Standardized Morphological Modeling and Simulation-Based Validation of a Novel Tibiotalar Fusion Implant. Bioengineering, 2025, 12(7), 705.

title: Standardized Morphological Modeling and Simulation-Based Validation of a Novel Tibiotalar Fusion Implant. Bioengineering, 2025, 12(7), 705.

A Self-Expanding Nitinol Fixation System for Atrial Leadless Pacemakers: Biomechanical Design and Evaluation.

title: A Self-Expanding Nitinol Fixation System for Atrial Leadless Pacemakers: Biomechanical Design and Evaluation.

Analysis of photocatalytic characteristics and mechanical properties of TiO2 thin films

title: Analysis of photocatalytic characteristics and mechanical properties of TiO2 thin films

Enhanced fracture fixation stability and osseointegration through over-compression: design of an annular compression plate for posterolateral tibial plateau fractures

title: Enhanced fracture fixation stability and osseointegration through over-compression: design of an annular compression plate for posterolateral tibial plateau fractures

Design of Battery Charger with USB Type-C Power Delivery Interface

title: Design of Battery Charger with USB Type-C Power Delivery Interface abstract: This paper proposes a new solution for USB Type-C power delivery (PD) chargers. This solution mainly adopts the integrated circuit (IC) AT6201Z designed by ATK. This IC has a multi-mode control strategy, which uses the Pseudo-Digital Loop (PDL) control method to change the operation mode of the converter according to the magnitude of the inductor current. PDL control method ensures loop stability and prevents system malfunctions. To prove the feasibility of the proposed solution, a prototype charger with a maximum switching frequency of 130kHz, output power of 100W, and input voltage range of 90-264Vac/50-60Hz, is designed and implemented. Based on the experimental results, the prototype has a maximum efficiency of 92%.

Development of Active-Clamp Flyback Converter for Improving Light-Load Efficiency

title: Development of Active-Clamp Flyback Converter for Improving Light-Load Efficiency abstract: Conventional active-clamp flyback (ACF) converters suffer increased conduction losses due to the extended conduction time of the auxiliary switch during light loads. To tackle this problem and improve light-load efficiency, this article proposes a novel control strategy. This strategy is designed to limit the generation of excessive conduction losses by the auxiliary switch during light loads. The proposed control strategy also employs the quasi-resonant (QR) valley switching (VS) technique within a single switching cycle to activate the auxiliary switch. This enables the main switch to achieve zero-voltage switching (ZVS) characteristics during its operation. Moreover, once the converter reaches medium loads, the auxiliary and main switches operate in a complementary manner with a fixed frequency. This operation allows both switches to achieve ZVS, leading to a significant reduction in switching losses. The operating principle and control strategy of the 65-W ACF converter with the novel control approach have been thoroughly analyzed and discussed. Experimental results have confirmed the effectiveness of this strategy, validating its ability to improve the overall efficiency of the converter under various load conditions.

A Hybrid Bidirectional Full-Bridge CLLC Resonant Converter With Dual-Resonant Frequency for Enhancing Efficiency at Light-to-Medium loads

title: A Hybrid Bidirectional Full-Bridge CLLC Resonant Converter With Dual-Resonant Frequency for Enhancing Efficiency at Light-to-Medium loads abstract: The symmetric capacitor-inductor-inductor-capacitor (CLLC) resonant converter is a key component in electric power conversion systems, used for interfacing with dc voltage buses in applications such as renewable energy sources, battery energy storage in electric vehicles (EVs), and dc microgrids. It is favored for its bidirectional power transfer, high power density, zero-voltage switching (ZVS) for primary power switches, and soft commutation for output rectifiers. However, a significant drawback of the CLLC converter is the high operating frequency at light loads, leading to increased switching losses and reduced efficiency. To overcome this problem, this article introduces a hybrid CLLC converter that can dynamically switch between full-bridge (FB) and half-bridge (HB) configurations, as well as adjust the resonant frequency based on load conditions. This hybrid approach allows the converter to operate in an HB configuration and adjust its resonant frequency, reducing the switching frequency during light-to-medium loads and thus enhancing operating efficiency. A prototype with a 2-kW power rating, designed to connect a 400-Vdc bus to an 800-Vdc bus, was tested. The experimental results confirmed the proposed converter’s effectiveness, demonstrating improved efficiency under light-to-medium load conditions.

Development of vacuum-chamber-type capacitive micro-pressure sensors

title: Development of vacuum-chamber-type capacitive micro-pressure sensors abstract: This study presents the development of a capacitive pressure sensor tailored for measuring the dynamic pressure of flow fields. The sensor is fabricated using the UMC 0.18 µm CMOS-MEMS process, incorporated with additional post-processing steps such as metal wet etching, supercritical CO2 drying, and parylene encapsulation. The sensing architecture employs AD7746 as a capacitance-to-voltage converter (CVC), enabling the conversion of capacitance signals into voltage outputs for enhanced measurement fidelity. Structurally, the capacitive pressure sensor features a vacuum-sealed diaphragm capsule design with dual movable circular membranes functioning as sensing electrodes. A contact-mode capacitive configuration with a trapezoidal or Gong-like vacuum-chamber diaphragm is adopted to improve linearity and sensitivity. The output sensitivity was determined to be feasible for measuring dynamic pressure at 1–2 Pa resolution.

MEMS flow sensors integration on flapping wings: advancements and application

title: MEMS flow sensors integration on flapping wings: advancements and application

MEMS modification of PDMS microchannels applied to the particle separation

title: MEMS modification of PDMS microchannels applied to the particle separation

Vacuum-chamber type capacitive micro pressure sensor using CMOS-MEMS

title: Vacuum-chamber type capacitive micro pressure sensor using CMOS-MEMS

Onsite measurement using CMOS MEMS flow sensors on rotating turbine blades

title: Onsite measurement using CMOS MEMS flow sensors on rotating turbine blades

MEMS on site measurement applied to wind turbines

title: MEMS on site measurement applied to wind turbines

Comparative analysis of leading-edge twisting mechanisms for flapping wings

title: Comparative analysis of leading-edge twisting mechanisms for flapping wings

A high sensitive nanomaterial coated side polished fiber sensor for detection of Cardiac Troponin I antibody

title: A high sensitive nanomaterial coated side polished fiber sensor for detection of Cardiac Troponin I antibody abstract: The advent of evanescent field based fiber optic biosensor and advancements in nanotechnology has create an excellent opportunity in label-free detection of biomarkers which plays vital role in the early, rapid and accurate diagnosis of acute diseases. In this work, we demonstrate a high sensitive Molybdenum Tungsten Disulfide (MoWS2) coated side polished fiber (SPF) biosensor for accurate and early diagnosis of cardio vascular disease (CVD). The Cardiac Troponins I (cTnI) is identified as a biomarker of interest for early and rapid diagnosis of CVD. The proposed SPF biosensor exhibits surface plasmonic resonance (SPR) detection due to the evanescent field interaction between MoWS2 nano coated side polished region and anti-CTnI. The proposed SPF biosensor possess the high sensitivity of 82% to detect the cTnI antibody with a limit of detection (LOD) about 17.5 pg/mL. The peak SPR shift have been calculated as 61 nm for analyte concentrations of 500 pg/mL Moreover, the proposed SPF biosensor possess the high degree of selectivity and environmental stability to CTnI among three analytes such as CTnI, Estrogen and Glucose. The hydrophobic interactions of MoWS2 and cTnI antibody leads to chemical free biofunctionalization of antibody in the sensing region. Hence, the simulation results shows the surface interaction strength calculated as 1.29 KJ mol−1/nm2 in order to evaluate the hydrophobic interactions. Thus, the proposed optical biosensor is a promising candidate for “point-of-care” testing of CVD disorders and preclinical assessments.

An internal real-time microscopic monitoring and diagnostic tool for improved proton battery stacks

title: An internal real-time microscopic monitoring and diagnostic tool for improved proton battery stacks abstract: Proton batteries have brought new research directions in the field of fuel cells and energy storage. Although our R&D team has developed a prototype of the proton battery stack, there are still some problems to be solved, such as leakage and unstable power generation. In addition, simultaneously and accurately measuring multiple key physical parameters inside a proton battery stack remains challenging. The present measurement methods are external or single parameters, that has become a limiting factor. These parameters (voltage, current, temperature, flow, humidity, pressure, oxygen and hydrogen) significantly affect the performance, life and safety of the proton battery stack. To address these challenges, this study developed a micro hydrogen sensor using the Micro-electro-mechanical systems (MEMS) technology, which was integrated with the previously developed seven-in-one microsensor, the mask and layout were re-designed to increase the number of microsensors, which were combined with a Flexible Printed Circuit (FPC). Finally, the development of a flexible eight-in-one microsensor was completed, so as to improve the output and overall operating efficiency of the microsensor, and provide a reliable internal multi-parameter real-time microscopic monitoring and diagnostic tool for the development of proton battery stacks.

Sensors-on-flapping-wings (SOFW) using complementary-metal-oxide-semiconductor (CMOS) MEMS technology

title: Sensors-on-flapping-wings (SOFW) using complementary-metal-oxide-semiconductor (CMOS) MEMS technology abstract: This article presents a framework of using MEMS sensors to investigate unsteady flow speeds of a flapping wing or the new concept of sensors on flapping wings (SOFWs). Based on the implemented self-heating flow sensor using U18 complementary metal–oxide–semiconductor (CMOS) MEMS foundry provided by the Taiwan Semiconductor Research Institute (TSRI), the compact sensing region of the flow sensor was incorporated for in situ diagnostics of biomimetic flapping issues. The sensitivity of the CMOS MEMS flow sensor, packaged with a parylene coating of 10 μm thick to prolong the lifetime, was observed as −3.24 mV/V/(m/s), which was below the flow speed of 6 m/s. A comprehensive investigation was conducted on integrating CMOS MEMS flow sensors on the leading edge of the mean aerodynamic chord (m.a.c.) of the flexible 70-cm-span flapping wings. The interpreted flow speed signals were checked and demonstrated similar behavior with the (net) thrust force exerted on the flapping wing, as measured in the wind tunnel experiments using the force gauge. The experimental results confirm that the in situ measurements using the concept of SOFWs can be useful for measuring the aerodynamic forces of flapping wings effectively, and it can also serve for future potential applications.

A parametric study and tailored infill design for enhanced flame-retardant performance of SORPLAS in FFF 3D printing

title: A parametric study and tailored infill design for enhanced flame-retardant performance of SORPLAS in FFF 3D printing abstract: This study employs recycled polycarbonate-based SORPLAS Impact as the material for Fused Filament Fabrication (FFF) in order to systematically investigate the effect of multiple printing parameters on flame-retardant performance. Four key parameters—infill pattern, infill density, primary layer height, and external solid layer thickness—were varied to fabricate test specimens, which were then subjected to combustion tests, thermal imaging, and grayscale analyses for quantitative evaluation. Temperature distribution and char formation behaviors were recorded during burning, and analysis of variance (ANOVA) along with Tukey’s HSD comparisons was used to identify the critical factors influencing flame retardancy. The results show that infill density and external solid layer thickness significantly affect ignition time, flame propagation, and post-combustion structural integrity. While moderate increases in material content promote stable char formation and effective thermal insulation, excessive accumulation can lead to expansion and deformation. Grayscale variations in thermal images further verify how each parameter set influences heat conduction and char formation. Overall, the findings demonstrate that carefully balancing these printing parameters and material usage can enhance flame retardancy and mechanical properties of 3D-printed parts, while also aligning with sustainability objectives. This work provides practical guidelines for advancing recycled flame-retardant materials and their applications in additive manufacturing.

Investigating Experimental and Computational Fluid Dynamics of 3D-Printed TPMS and Lattice Porous Structures

title: Investigating Experimental and Computational Fluid Dynamics of 3D-Printed TPMS and Lattice Porous Structures abstract: This study investigates the capillary performance and wetting behavior of SLA (Stereolithography) 3D-printed porous structures, focusing on TPMS (triply periodic minimal surfaces)-Gyroid, Octet, Diamond, and Isotruss lattice designs. High-speed imaging was used to analyze droplet interactions, including penetration, spreading, and contact angles, with 16 μL water droplets dropping from 30 mm at 0.77 m/s. Results showed variable contact angles, with Isotruss and Octet having higher angles, while Diamond faced measurement challenges due to surface roughness. Numerical simulations of TPMS-Gyroid of 2 mm3 unit cells validated the experimental results, and Diamond, Octet, and Isotruss structures were simulated. Capillary performance was assessed through deionized (DI) water weight–time (w-t) measurements, identifying that the TPMS-Gyroid structure performed adequately. Structures with 4 mm3 unit cells had low capillary performance, excluding them from permeability testing, whereas smaller 2 mm3 structures demonstrated capillary effects but had printability and cleaning issues. Permeability results indicated that Octet performed best, followed by Isotruss, Diamond, and TPMS-Gyroid. Findings emphasize unit cell size, beam thickness, and droplet positioning as key factors in optimizing fluid dynamics for cooling, filtration, and fluid management.

Numerical Simulation of Permeability for Novel Lattice Structures Under Various Flow Conditions

title: Numerical Simulation of Permeability for Novel Lattice Structures Under Various Flow Conditions abstract: Porous materials are essential in applications like impact absorption, thermal management, tissue engineering, and vibration damping, making their detailed study crucial. Key parameters in pore structure characterization include porosity, pore distribution, types, aperture size, shape, tortuosity, pore size distribution, specific surface area, and permeability. This study numerically simulates the permeability of two Triply Periodic Minimal Surfaces (TPMS) structures—Primitive and Gyroid—and two strut-based lattice structures—Diamond and Iso-truss. The analysis was conducted under steady-state conditions, with variations in porosity levels (60%, 70%, 80%, 90%), Reynolds numbers (Re) of 10, 50, 100, 150, 200, and 250, and a lateral length of 3 mm. Results indicate that higher porosity correlates with higher permeability, while increasing Re lead to higher pressure drops, reducing permeability. Among the structures, the lattice Diamond shows the highest permeability, while TPMS Primitive generally has the lowest.

Enzymatic glucose fiber sensor for glucose concentration measurement with a heterodyne interferometry

title: Enzymatic glucose fiber sensor for glucose concentration measurement with a heterodyne interferometry abstract: In this study, we developed a glucose fiber sensor incorporating heterodyne interferometry to measure the phase difference produced by the chemical reaction between glucose and glucose oxidase (GOx). Both theoretical and experimental results showed that the amount of phase variation is inversely proportional to glucose concentration. The proposed method provided a linear measurement range of the glucose concentration from 10 mg/dL to 550 mg/dL. The experimental results indicated that the sensitivity is proportional to the length of the enzymatic glucose sensor, and the optimum resolution can be obtained at a sensor length of 3 cm. The optimum resolution of the proposed method is better than 0.6 mg/dL. Moreover, the proposed sensor demonstrates good repeatability and reliability. The average relative standard deviation (RSD) is better than 10% and satisfied the minimum requirement for point-of-care devices.

Notes on the uniqueness of Type II Yamabe metrics

title: Notes on the uniqueness of Type II Yamabe metrics abstract: In this paper, we study the uniqueness of type II Yamabe metrics in conformal classes on a compact connected manifold with boundary, and we investigate Obata-type theorems for type II Yamabe metrics. In particular, we establish a theorem which gives a sufficient condition for a metric to be the unique Type II Yamabe metric in its conformal class. We also prove the corresponding theorem for the CR Yamabe problem on closed manifolds.

Some results on the weighted Yamabe problem with or without boundary

title: Some results on the weighted Yamabe problem with or without boundary abstract: Abstract. Let (Mn,g,e− ϕdVg,e− ϕdAg,m) be a compact smooth metric measure space with boundary with n ⩾ 3. In this article, we consider several Yamabe-type problems on a compact smooth metric measure space with or without boundary: uniqueness problem on the weighted Yamabe problem with boundary, characterization of the weighted Yamabe solitons with boundary and the existence of positive minimizers in the weighted Escobar quotient.

Optimizing implant lattice design for large distal femur defects: Stimulating interface bone growth to enhance osseointegration

title: Optimizing implant lattice design for large distal femur defects: Stimulating interface bone growth to enhance osseointegration abstract: Large bone defects in the distal femur present a significant challenge due to the lack of inherent self-healing capabilities. Traditional approaches, such as utilizing polymethyl methacrylate (PMMA) in conjunction with a plate for distal femur reconstruction, have shown unsatisfactory osseointegration outcome, which leads to complications. To address this challenge, this study focuses on developing a lattice-structured implant for reconstructing distal femoral bone defects. The lattice geometry is based on the cuboctahedron lattice, with its design optimized through the adjustment of pillar diameter and arrangement angle. The lattice structure is designed to stimulate the surrounding bone, ultimately enhancing osseointegration in distal femur reconstruction. Finite element analysis revealed that for promoting bone ingrowth toward the implant, setting the optimal lattice structure parameters, i.e., a 45° arrangement angle and a 0.8 mm pillar diameter, is required. Fabricated using state-of-the-art metal three-dimensional printing, the implant underwent rigorous validation through biomechanical testing, in vitro biological assays, and animal experiments. The comprehensive results affirmed the bioactivity of the lattice-structured implant, underscoring its capability to improve osseointegration in distal femoral defect reconstruction.

Injectable ChitHCl-DDA tissue adhesive with high adhesive strength and biocompatibility for torn meniscus repair and regeneration

title: Injectable ChitHCl-DDA tissue adhesive with high adhesive strength and biocompatibility for torn meniscus repair and regeneration abstract: Suture pull-through is a clinical problem in meniscus repair surgery due to the sharp leading edge of sutures. Several tissue adhesives have been developed as an alternative to traditional suturing; however, there is still no suitable tissue adhesive specific for meniscus repair treatment due to unsatisfactory biosafety, biodegradable, sterilizable, and tissue-bonding characteristics. In this study, we used a tissue adhesive composed of chitosan hydrochloride reacted with oxidative periodate-oxidized dextran (ChitHCl-DDA) combined with a chitosan-based hydrogel and oxidative dextran to attach to the meniscus. We conducted viscoelastic tests, viscosity tests, lap shear stress tests, Fourier transform infrared (FTIR) spectroscopy, swelling ratio tests, and degradation behavior tests to characterize these materials. An MTT assay, alcian blue staining, migration assay, cell behavior observations, and protein expression tests were used to understand cell viability and responses. Moreover, ex vivo and in vivo tests were used to analyze tissue regeneration and biocompatibility of the ChitHCl-DDA tissue adhesive. Our results revealed that the ChitHCl-DDA tissue adhesive provided excellent tissue adhesive strength, cell viability, and cell responses. This tissue adhesive has great potential for torn meniscus tissue repair and regeneration.

A study to predict the hydrodynamic and thermal characteristics of hybrid mesh regenerator

title: A study to predict the hydrodynamic and thermal characteristics of hybrid mesh regenerator abstract: A Stirling engine is a heat engine that utilizes the cyclic compression and expansion of the working fluid caused by differential temperature for its operation. The regenerator heat exchanger is one of the core components in these Stirling engines, and the performance of the regenerator determines the performance of the Stirling engine. So, in this project, experimental and numerical simulations have been performed to study and compare the thermal and hydrodynamic properties of single mesh and hybrid mesh regenerators. Both single flow and oscillating flow characteristics were studied for single mesh regenerators with wire screens of mesh numbers 300, 400, 500 and hybrid mesh regenerators with wire mesh numbers 300-400-500 and 500-400-300. The oscillating flow study was carried out for 700 RPM, 500 RPM, 300 RPM and 200 RPM. It was observed that the single mesh regenerator with 500 mesh screens has the highest amount of energy storage but at the same time, it was also observed that the 500 mesh has the highest amount of pressure loss gradient. Upon comparing the pressure loss gradient and energy storage it was observed that the hybrid mesh has a better performance as it can store more heat energy with less pressure loss. A correlation was also developed for estimation of the Nusselt number.

Numerical Analysis to Find Permeability of Lattice Structures

title: Numerical Analysis to Find Permeability of Lattice Structures abstract: As the need for efficient heat extraction grows with decreasing extraction areas, enhancing heat transfer device performance is crucial. Porous structures in thermal devices like heat pipes and vapor chambers can significantly improve heat transfer. Permeability, vital in fluid dynamics, affects fluid flow in porous materials, such as lattice structures. This study uses numerical analysis to assess the permeability of lattice structures, created using nTopology and analyzed with ANSYS Fluent software. It focuses on Octet, Isotruss, and Diamond lattice geometries. The research considers lattice geometry, unit cell characteristics, flow conditions, and other factors to deeply understand these structures' behavior. Insights into how different parameters influence lattice behavior and permeability are gained. The study also examines the impact of beam thickness and porosity on lattice performance. By varying and comparing these aspects, the study seeks to develop a more thorough framework for permeability research, contributing to advancements in lattice structure design and engineering applications.

CR Paneitz operator and its application in CR geoemtry

title: CR Paneitz operator and its application in CR geoemtry

Noncompactness of the constant scalar curvature and constant boundary mean curvature equation

title: Noncompactness of the constant scalar curvature and constant boundary mean curvature equation

The weighted conformal mean curvature flow

title: The weighted conformal mean curvature flow

Equivariant CR Yamabe problem

title: Equivariant CR Yamabe problem abstract: As a generalization of the Yamabe problem, Hebey and Vaugon considered the equivariant Yamabe problem: for a subgroup G of the isometry group, find a G-invariant metric whose scalar curvature is constant in a given conformal class. In this paper, we introduce the equivariant CR Yamabe problem and prove some related results.

Extending CR Yamabe flow and Yamabe flow with boundary

title: Extending CR Yamabe flow and Yamabe flow with boundary

Deformations of the scalar curvature of a partially integrable pseudohermitian manifold

title: Deformations of the scalar curvature of a partially integrable pseudohermitian manifold abstract: We consider deformations of the scalar curvature of a partially integrable pseudohermitian manifold, in analogy with the work of Fischer and Marsden on Riemannian manifolds. In particular, we introduce and discuss R-singular spaces, give sufficient conditions for the stability of the scalar curvature, and give a partial infinitesimal rigidity result for the scalar curvature of a compact, torsion-free, scalar-flat, integrable pseudohermitian manifold

A rigidity result for the product of spheres

title: A rigidity result for the product of spheres abstract: In this paper, we prove a rigidity result for the product metric on the product of spheres S1×Sn−1.

The second Yamabe invariant with boundary

title: The second Yamabe invariant with boundary abstract: Let (M,∂M,g) be a compact Riemannian manifold with boundary. As a generalization of the Yamabe invariant with boundary Y(M,∂M,g) , we define the kth Yamabe invariant with boundary Yk(M,∂M,g). We prove some of its properties and study when it can be attained by the generalized metric. We also prove a version of conformal Schwarz lemma on (M,∂M,g)by using the Yamabe flow with boundary.

Additive Manufacturing of Vapor Chambers

title: Additive Manufacturing of Vapor Chambers abstract: The increasing power density of high-performance electronic devices poses significant thermal management challenges. Vapor chambers (VCs) offer efficient heat dissipation, but traditional manufacturing methods limit their structural precision and performance. This study investigates the thermal performance of VCs fabricated with additive manufacturing (AM), featuring triply periodic minimal surface (TPMS) Gyroid capillary structures at two fill ratios under varying thermal loads. Enhanced thermal stability and performance were observed in the higher fill ratio, particularly under higher heat loads, whereas the lower fill ratio excelled under low-heat conditions, achieving a thermal resistance as low as 0.3688 K/W at an 80Wheat load. Additionally, the research explored the advantages and challenges of horizontal and vertical printing techniques in VC fabrication. Horizontal printing was found to compromise cavity volume due to necessary support structures, whereas vertical printing enhanced mass production feasibility and maintained effective vapor circulation. This study proposes a novel approach using AM to manufacture VCs as a monolithic structure. By eliminating the need for welding, this method ensures seamless integration of the capillary structure with the housing, thereby avoiding issues related to poor contact or welding-induced damage. The study confirmed a 75% reduction in thermal resistance in VCs with capillary structures compared to those without under similar conditions, highlighting the significant potential of integrating precisely designed capillary structures and additive manufacturing in improving vapor chamber performance for advanced thermal management applications.

奈米碳管複合銀纖維製作與熱傳性質

title: 奈米碳管複合銀纖維製作與熱傳性質