Web Layout Design of Large Cavity Structures Based on Topology Optimization

Large cavity structures are widely employed in aerospace engineering, such as thin-walled cylinders, blades andwings. Enhancing performance of aerial vehicles while reducing manufacturing costs and fuel consumptionhas become a focal point for contemporary researchers. Therefore, this paper aims to investigate the topologyoptimization of large cavity structures as a means to enhance their performance, safety, and efficiency. By usingthe variable density method, lightweight design is achieved without compromising structural strength. Theoptimization model considers both concentrated and distributed loads, and utilizes techniques like sensitivityfiltering and projection to obtain a robust optimized configuration. The mechanical properties are checked bycomparing the stress distribution and displacement of the unoptimized and optimized structures under the sameload. The results confirm that the optimized structures exhibit improved mechanical properties, thus offering keyinsights for engineering lightweight, high-strength large cavity structures.

Axially variable-length solid element of absolute nodal coordinate formulation

An axially variable-length solid element with eight nodes is proposed by integrating the arbitrary Lagrangian-Eulerian (ALE) formulation and the absolute nodal coordinate formulation (ANCF). In addition to the nodal positions and slopes of eight nodes, two material coordinates in the axial direction are used as the generalized coordinates. As a consequence, the nodes in the ALE-ANCF are not associated with any specific material points and the axial length of the solid element can be varied over time. These two material coordinates give rise to a variable mass matrix and an additional inertial force vector. Computationally efficient formulae of the additional inertial forces and elastic forces, as well as their Jacobians, are also derived. The dynamic equation of a flexible multibody system (FMBS) with variable-length bodies is presented. The maximum and minimum lengths of the boundary elements of an FMBS have to be appropriately defined to ensure accuracy and non-singularity when solving the dynamic equation. Three numerical examples of static and dynamic problems are given to validate the variable-length solid elements of ALE-ANCF and show their capability.

Remodeling the immune microenvironment for gastric cancer therapy through antagonism of prostaglandin E2 receptor 4

Gastric cancer is highly prevalent among digestive tract tumors.Due to the intri-cate nature of the gastric cancer immune microenvironment,there is currently no effective treatment available for advanced gastric cancer.However,there is promising potential for immunotherapy targeting the prostaglandin E2 receptor subtype 4(EP4)in gastric cancer.In our previous study,we identified a novel small molecule EP4 receptor antagonist called YY001.Treatment with YY001 alone demonstrated a significant reduction in gastric cancer growth and inhibited tumor metastasis to the lungs in a mouse model.Furthermore,adminis-tration of YYo01 stimulated a robust immune response within the tumor microenvironment,characterized by increased infiltration of antigen-presenting cells,T cells,and M1 macro-phages.Additionally,our research revealed that YYo01 exhibited remarkable synergistic ef-fects when combined with the PD-1 antibody and the clinically targeted drug apatinib,rather than fluorouracil.These findings suggest that YYo01 holds great promise as a potential therapeutic strategy for gastric cancer,whether used as a standalone treatment or in combination with other drugs.

High-power,electrically-driven continuous-wave 1.55-μm Si-based multi-quantum well lasers with a wide operating temperature range grown on wafer-scale InP-on-Si(100)heterogeneous substrate

A reliable,efficient and electrically-pumped Si-based laser is considered as the main challenge to achieve the integration of all key building blocks with silicon photonics.Despite the impressive advances that have been made in developing 1.3-μm Si-based quantum dot(QD)lasers,extending the wavelength window to the widely used 1.55-μm telecommunication region remains difficult.In this study,we develop a novel photonic integration method of epitaxial growth of III-V on a wafer-scale InP-on-Si(100)(InPOS)heterogeneous substrate fabricated by the ion-cutting technique to realize integrated lasers on Si substrate.This ion-cutting plus epitaxial growth approach decouples the correlated root causes of many detrimental dislocations during heteroepitaxial growth,namely lattice and domain mismatches.Using this approach,we achieved state-of-the-art performance of the electrically-pumped,continuouswave(CW)1.55-μm Si-based laser with a room-temperature threshold current density of 0.65 kA/cm^(-2),and output power exceeding 155mW per facet without facet coating in CW mode.CW lasing at 120℃ and pulsed lasing at over 130℃ were achieved.This generic approach is also applied to other material systems to provide better performance and more functionalities for photonics and microelectronics.

Deployment dynamics and topology optimization of a spinning inflatable structure

Inflatable space structures may undergo the vibration of a long duration because of their features of dynamic deployment,high flexibility,and low-frequency modes.In this paper,a topology optimization methodology is proposed to reduce the vibration of a spinning inflatable structure.As the first step,a variable-length shell element is developed in the framework of arbitrary Lagrange-Euler(ALE)and absolute nodal coordinate formulation(ANCF)to accurately model the deployment dynamics of the inflatable structure.With the help of two additional material coordinates,the shell element of ALE-ANCF has the ability to describe the large deformation,large overall motion,and variable length of an inflatable structure.The nonlinear elastic forces and additional inertial forces induced by the variable length are analytically derived.In the second step,a topology optimization procedure is presented for the dynamic response of an inflatable structure through the integration of the equivalent static loads(ESL)method and the density method.The ESL sets of the variable-length inflatable structure are defined to simplify the dynamic topology optimization into a static one,while the density-based topology optimization method is used to describe the topology of the inflatable structure made of two materials and solve the static optimization problem.In order to obtain more robust optimization results,sensitivity analysis,density filter,and projection techniques are also utilized.Afterwards,a benchmark example is presented to validate the ALE-ANCF modeling scheme.The deployment dynamics and corresponding topology optimization of a spinning inflatable structure are studied to show the effectiveness of the proposed topology optimization methodology.

用于制备具有超光滑表面异质集成4英寸硅基砷化镓薄膜的高效离子剥离技术

在Si衬底上将单晶GaAs薄膜与其进行异质集成有望为硅基光电集成提供新的材料平台.本文基于对GaAs材料剥离机理的分析阐述,优化了GaAs薄膜转移工艺的离子注入条件.结果表明,相比于He离子单独注入,由于较小的热预算和注入后相对更低的缺陷密度,He/H离子共注入对于GaAs薄膜转移更高效.以Al2O3为键合介质层,通过优化的离子剥离技术成功地将4英寸GaAs薄膜转移到Si(100)衬底上.探索了包括化学机械抛光、臭氧辐照氧化和KOH清洗的表面处理工艺,以将转移后GaAs薄膜的表面质量提高到可以高质量外延的水平.在400℃退火1 h后,转移的GaAs薄膜单晶质量进一步提高,X射线摇摆曲线的半峰全宽仅为89.03 arcsec.

Wave control of a flexible space tether based on elastic metamaterials

This study proposes a spider‐web elastic metamaterial to suppress vibrations in space slender structures,such as flexible space tethers.The metamaterial consists of unit cells that are periodically distributed on the space tether to obtain band gaps.The finite element model of the unit cell is established by employing the absolute nodal coordinate formulation(ANCF)due to the large deformation of the structure.The eigenfrequencies and corresponding vibration modes of the unit cell are obtained by ANCF.Moreover,the band gap of the unit cell is calculated based on the phonon crystal theory.The relationship between the vibration modes and the band gaps is analyzed.Finally,an experiment is conducted to verify the vibration transmission characteristics of finite period cells.The results show the effectiveness of the spider‐web elastic metamaterial for vibration suppression of a flexible tether.This study provides insights into the use of elastic metamaterials for vibration isolation in space tether systems.

Thermally tunable GeSi electro-absorption modulator with a wide effective operating wavelength range

We demonstrate a GeSi electro-absorption modulator with on-chip thermal tuning for the first time,to the best of our knowledge.Theoretical simulation proves that the device temperature can be tuned and the effective operating wavelength range can be broadened.When the heater power is 4.63 mW,the temperature of the waveguide increases by about 27 K and the theoretical operating wavelength range is broadened by 23.7 nm.The experimental results show that the optical transmission line shifted to the longer wavelength by 4.8 nm by every 1 mW heater power.The effective static operating wavelength range of the device is increased from 34.4 nm to 60.1 nm,which means it is broadened by 25.7 nm.The band edge shift coefficient of 0.76 nm/K is obtained by temperature simulation and linear fitting of the measured data.The device has a 3 dB EO bandwidth of 89 GHz at 3 V reverse bias,and the eye diagram measurement shows a data rate of 80 Gbit/s for non-return-to-zero on–off keying modulation and 100 Gbit/s for 4 pulse amplitude modulation in the 1526.8 nm to 1613.2 nm wavelength range as the heater power increases from 0 mW to 10.1 mW.