Assembly Scheme Research Articles

Modular scaffolds with intelligent visual guidance system for in situ bone tissue repair

Abstract In clinical practice, the irregular shapes of traumas pose a significant challenge in rapidly manufacturing personalized scaffolds. To address these challenges, inspired by LEGO® bricks, this study proposed a novel concept of modular scaffolds and developed an innovative system based on machine vision for their rapid and intelligent assembly tailored to defect shapes. Trapezoidal interfaces effectively connect standardized bone units based on magnesium-doped silicate calcium, ensuring high stability of the modular scaffolds (compressive strength up to 135 MPa and bending strength up to 17 MPa). Through self-developed defect recognition and reconstruction algorithms, defect recognition and personalized assembly schemes for bone scaffolds can be achieved autonomously. Modular scaffolds seamlessly integrate with surrounding bone tissue, promoting new bone growth, with no apparent differences compared to fully 3D printed integral scaffolds in the skull and femur repair experiments. In summary, the adoption of modular scaffolds not only integrates personalization and standardization but also satisfies the optimal treatment window.

Eucalyptus-Based Glued Laminated Timber: Evaluation and Prediction of Its Properties by Non-Destructive Techniques

Eucalyptus-based glued laminated timber (glulam) was produced to determine the feasibility of a non-destructive method (drilling resistance) to predict the properties of structural elements and add value to lower-quality hardwood species. Glulam was manufactured with formaldehyde (Resorcinol), reference condition, and bio-based (Castor oil-based) adhesives in two assembly schemes, the core composed either of two continuous lamellae each 105 cm long, or of two formed by the juxtaposition of shorter boards (35 and 55 cm). The shear strength of the glue line (fv0), modulus of elasticity (Ec90), and strength (fc90) in compression perpendicular to the grain; delamination (DL); and main and extended glue line thicknesses were evaluated. The Resistograph equipment was used to perform the perforation perpendicular to the glue line (samples extracted from the glulam elements) to correlate the properties. The results of this research demonstrate that the scheme of the boards had little effect on the physical and mechanical properties evaluated (except the main glue line and delamination), and the drilling resistance (DR) presents a significant correlation with practically all properties evaluated (variations in density values and other properties are explained by variations in DR values), making it possible to estimate Ec90 and fc90 with desired precision (R2adj ≈ 80%). This highlights the feasibility of using this methodology in the quality control of glulam elements. It is concluded that regardless of the adhesive, elements comprising a 105 cm-length core and external lamellae (T1 and control) are indicated for external use, presenting low delamination. Short-length central lamellae adhesively glued with PUR (T2) are not recommended for external applications due to their susceptibility to delamination. However, T2 is indicated for internal environments due to its low production cost. This study also proved the efficiency of using models based on drilling resistance to estimate wood density and its resistance to compression perpendicular to the fiber.

Analysis of the assembly pressure of a high-power molten carbonate fuel cell stack during initial roasting

This study investigated the effect of the assembly pressure during the initial roasting of a 15 kW molten carbonate fuel cell (MCFC) stack on its performance, with the aim of enhancing the success rate of large-area, high-power stacks. The corresponding assembly scheme was designed to possess an intermediate intake structure for ensuring a uniform intake distribution along the vertical axis of the MCFC stack. Monitoring the correlation between the settling distance of the MCFC stack and roasting temperature revealed the crucial stage of diaphragm roasting and identified the appropriate compensation period for pressure loss, thereby enhancing the success rate of the initial roasting process. At an assembly pressure of 4.35 MPa, the MCFC stack exhibited a constant voltage of 84 V, achieving a maximum output power of 16.51 kW and discharge current density exceeding 95 mA/cm2, thereby confirming the effectiveness of the assembly scheme and initial roasting process.

Anisotropic swelling pressures of compacted GMZ bentonite infiltrated with salt solutions

In the high-level radioactive waste (HLW) deep geological repository, bentonite is compacted uniaxially, and then arranged vertically in engineered barriers. The assembly scheme induces the initial anisotropy, and with hydration, it develops more evidently under chemical conditions. To investigate the anisotropic swelling of compacted Gaomiaozi (GMZ) bentonite and the further response to saline effects, a series of constant-volume swelling pressure tests were performed. Results showed that dry density enhanced the bentonite swelling and raised the final anisotropy, whereas saline inhibited the bentonite swelling but still promoted the final anisotropy. The final anisotropy coefficient (ratio of radial to axial pressure) obeyed the Boltzmann sigmoid attenuation function, decreasing with concentration and dry density, converging to a minimum value of 0.76. The staged evolution of anisotropy coefficient was discovered, that saline inhibited the rise of the anisotropy coefficient (Δδ) in the isotropic process greater than the valley (δ1) in the anisotropic process, leading to the final anisotropy increasing. The isotropic stage amplified the impact of soil structure rearrangement on the macro-swelling pressure values. Thus, a new method for predicting swelling pressures of compacted bentonite was proposed, by expanding the equations of Gouy-Chapman theory with a dissipative wedge term. An evolutionary function was constructed, revealing the correlation between the occurrence time and the pressure value due to the structure rearrangement and the former crystalline swelling. Accordingly, a design reference for dry density was given, based on the chemical conditions around the pre-site in Beishan, China. The anisotropy promoted by saline would cause a greater drop of radial pressure, making the previous threshold on axial swelling fail.

Design Principles for Fast and Efficient Self-Assembly Processes

Self-assembly is a fundamental concept in biology and of significant interest to nanotechnology. Significant progress has been made in characterizing and controlling the properties of the resulting structures, both experimentally and theoretically. However, much less is known about kinetic constraints and determinants of dynamical properties like time efficiency, although these constraints can become severe limiting factors of self-assembly processes. Here, we investigate how the time efficiency and other dynamical properties of reversible self-assembly depend on the morphology (shape) of the building blocks for systems in which the binding energy between the constituents is large. As paradigmatic examples, we stochastically simulate the self-assembly of constituents with triangular, square, and hexagonal morphology into two-dimensional structures of a specified size. We find that the constituents’ morphology critically determines the assembly time and how it scales with the size of the target structure. Our analysis reveals three key structural parameters defined by the morphology: the nucleation size and attachment order, which describe the effective order of the chemical reactions by which clusters nucleate and grow, respectively, and the growth exponent, which determines how the growth rate of an emerging structure scales with its size. Using this characterization, we formulate an effective theory of the self-assembly kinetics, which we show exhibits an inherent scale invariance. This allows us to identify general scaling laws that describe the minimal assembly time as a function of the size of the target structure. We show how these insights on the kinetics of self-assembly processes can be used to design assembly schemes that could significantly increase the time efficiency and robustness of artificial self-assembly processes. Published by the American Physical Society 2024

Influence of Liner Surface with Parameterized Pit Texture on the Friction Characteristics of Piston Rings

The arrangement of a pit-shaped surface texture on the surface of a cylinder liner significantly affects reductions in piston ring friction, and the influence of the structural parameters and spatial distribution on piston ring friction power consumption is unclear. In this paper, the diameter, depth, axial spacing distance, and radial spacing distance of the pits on the inner surface of a cylinder liner were used as variable parameters to process the surface textures of different schemes, and then a friction and wear test was carried out on UMT piston ring–cylinder liner specimens, several texture schemes with the best anti-friction effect were selected, an engine bench test was carried out by comparing these texture schemes with non-texture schemes, and the frictional torque and fuel consumption of the engine were studied at different oil temperatures. The results show that the depth of the pits in the surface texture of a cylinder liner has a greater influence on the friction reduction effect, followed by the radius. The higher the oil temperature in the engine bench test, the greater the impact of the surface texture. The reduction in fuel consumption was greater in the lower-speed region after structuring the textured cylinder liner compared to the non-textured cylinder liner. Specifically, the friction coefficient was mainly affected by the depth of the pits, and the depths of the pits in the texture schemes with good friction reduction effect were all 17–19 μm. The best friction reduction could be achieved when the pit radius is around 50 μm, with little difference in pit depth. When the oil temperature was 95 °C, the average drag torque reduction was about 1.69 Nm; when the oil temperature was 105 °C, the decrease was about 2.54 Nm; and when the oil temperature was 105 °C, the decrease was about 4.53 Nm. After adding the surface texture of the cylinder liner, the fuel consumption rate of the engine equipped with the structured cylinder liner was generally reduced compared with that of the original cylinder liner engine. Among them, the average and subsequent consumption rate of surface assembly scheme 11 decreased the most, with a value of 1.3 g/kwh.

FEATURES OF BEHAVIOR AND CALCULATION OF DOWEL TIMBER JOINTS WITH SLOTTED-IN PLATES ACCORDING TO EC5

The paper presents an overview of theoretical and experimental studies of connections of timber structures with steel dowel with steel slitted-in plates. The correct choice of the type of connections allows you to significantly influence the total cost of the structure due to the formation of thestructural and assembly scheme of the structure (minimization of the number of nodal and assembly connections), optimal unification of connections isan additional argument for creating an economical and competitive solution. For the analysis of the dowel connection, it is taken into account that theforce is transmitted due to the bending and shear resistance of the fastening element, as well as crumpling in the connected timber elements. The limitstates of the dowel joint are considered loss of strength due to crumpling and splitting of the wood of the hole wall, as well as due to bending of the nailin the nail socket. The works considered in the review provide extensive factual material on the strength of connections depending on the geometricand physical parameters of its components, as well as the stiffness of the connection, which is currently the subject of active attention of researchers. Attention is paid to the need to study the operation of nodes under the action of a moment during group operation of the connection. The analysis of numerous experiments makes it possible to check the reliability of the current design rules and norms of EC5 and the design norms of DBN В.2.6-161:2017 implemented to them, and also revealed the shortcomings and limits of the application of the design rules for this type. connections The results of numerical and experimental studies are the basis for improvingthe structural solutions of the joints of wooden elements and allowed to accumulate significant factual material for the verification of numerical simulation models.

Assembly of (2×C2+C’2)×n Molecular Complexity Using a Sequence of Pt‐ and Pd‐Catalyzed Transformations with Calcium Carbide

AbstractConstructing molecular complexity from simple precursors stands as a cornerstone in contemporary organic synthesis. Systems harnessing easily accessible starting materials, which offer control over stereochemistry and support a modular assembly approach, are particularly in demand. In this research, we utilized calcium carbide, presenting a sustainable pathway to generate acetylene gas – a fundamental C2 building block. We performed a Pt‐facilitated linkage of two C2‐units sourced from two calcium carbide molecules to craft a conjugated C4 core with exceptional stereoselectivity. As a benchmark, we selected the synthesis of (E,E)‐1,4‐diiodobuta‐1,3‐diene, executing it in a two‐chamber reactor. Compartmentalization of the reactions across these chambers resulted in the desired product in 85% yield. Furthermore, high‐energy polymeric substances were derived by marrying the molecular intricacy between (E,E)‐1,4‐diiodobuta‐1,3‐diene and calcium carbide, underpinning a unique C4+C2 assembly blueprint. The structure and morphology of the polymeric material were characterized by IR and NMR spectroscopy, scanning electron microscopy, and energy dispersive X‐ray spectroscopy. Overall, two complementary 2×C2‐to‐C4 and (2×C2+C’2)×n assembly schemes were developed using Pt and Pd catalysis.

Localized spin-selective interference assisted broadband tunable chirality with diatomic all-dielectric metasurfaces

Chiral metasurfaces with spin-selective properties have shown an unprecedented ability to modulate optical properties on the subwavelength scale. Alternatively, the simultaneous implementation of broadband tunable chiral response and wavefront manipulation on minimalistically constructed monolayer metasurfaces can lead to a plethora of applications such as optical converter diodes, chiral imaging, and sensing. Benefiting from a localized interference between two pairs of achiral meta-atoms whose optical behavior is similar to that of a half-wave plate (HWP), we theoretically provide a design strategy for constructing meta-molecules for asymmetric transmission (AT) parameters using interference mechanisms, each of which achieves a specific modulation function in the terahertz (THz) band. Localized interference effects with polarization-selective properties permit the incident circular polarization to be transformed into its orthogonal polarization mode. Benefiting from spin-selective transmission, the proposed metasurface simultaneously implements polarization filtering and wavefront manipulation with the assistance of a geometric phase mechanism. Not only that, chiral imaging schemes are also evaluated under such a design mechanism. As a result, this generalized assembly scheme can not only be extended to arbitrary working bands, but also find a variety of applications in photodetectors.

Review and challenges for the remanufacturing assembly quality with uncertainty

Remanufacturing businesses have difficulty in competing and expanding due to the unpredictable quality and performance of remanufactured products. It has turned into a problem area and a bottleneck for the growth of the remanufacturing sector. The control and management of remanufactured assembly quality (RAQ) is considered one of the key factors affecting the quality of remanufactured products. By reviewing existing literature, we have found that in remanufacturing assembly systems, the uncertainty of remanufacturing components, the volatility of remanufacturing assembly processes, the complexity of assembly control, and the diversity of assembly schemes are the main reasons for the difficulty in ensuring assembly quality. However, existing literature lacks research on data management, evolutionary mechanisms of RAQ, and multivariate control. To improve the stability of RAQ and improve the quality of remanufactured products, we propose the construction of an intelligent reasoning mode for precise RAQ control and a tailored, intelligent control method for individual components, providing support for the intelligent control of remanufactured assembly functional modules. This study provides a basis for implementing high-performance assembly technology for remanufactured products. Our findings should encourage the industry’s modernization for remanufacturing.

Bistable morphology analysis of the flexible single-vertex origami unit cell

In origami structures, it is necessary to study the novel properties of the single-vertex origami unit cell first, which is the basic unit that could be assembled into a large-scale origami tessellation with complex patterns. When the elasticity of the sheet and the kinematics of the crease are combined, nearly all single-vertex origami unit cells with an arbitrary crease pattern are foldable and bistable. In this case, the stable morphology of the unit cell is dominated by both the crease rotation and the shell deformation. In this work, two models are proposed for the solution of the bistability of the flexible origami unit cell. First, a flexible boundary conical shell model is proposed, by introducing crease mechanics based on the previous work. This linear model can be easily solved for flexible f-cones with arbitrary crease patterns by a certain assembly scheme. Moreover, to consider the nonlinearity, the discrete creased model (DCM) is further developed for the stable state solution of the arbitrary origami unit cell. Thereafter, the results obtained by the two models are verified with the corresponding FE simulations. Based on the normalized crease stiffness, the coupling effect between the crease and the shell is analyzed. The core deformation mechanism of flexible origami unit cells is classified into three cases: the crease-dominated case, the crease-shell coupled case, and the shell-dominated case. Additionally, the energy ratio of crease rotation to shell bending at the snapping state is found to be approximately proportional to the normalized crease stiffness.

Optimization Analysis on the Transmission Characteristics of Multipurpose Power Transmission Devices

Particularly crucial throughout the mode transition procedure is the transmission properties of hydro–mechanical composite transmission devices. This paper describes a multipurpose power transmission device that integrates hydrostatic, hydro-mechanical, and mechanical transmission and mainly discusses the transmission characteristic optimization problem from the perspective of speed regulation characteristics, shift strategy, and efficiency characteristics. The kinematic and dynamic analysis of the transmission system, the assembly scheme, and relevant parameters of the power transmission device are analyzed, and the speed regulation characteristic curve is obtained. The shift strategy of power transmission devices involving clutches and brakes during the whole speed regulation process and the best switch time of each component are found. The efficiency expression of the static pressure system is obtained from the efficiency model of the pump-control-motor system, and the efficiency of the multi-purpose power transmission device is obtained using the efficiency definition method. The fitting curves of hydrostatic system efficiency are determined using experimental data, and the efficiency of the hydro–mechanical composite power transmission system is obtained using the conversion mechanism method. The results show that the shift quality of power transmission devices can be improved greatly by controlling the switch sequence of clutches and brakes reasonably.

Evaluation of anxiety among participants in concrete structure assembly schemes based on cognitive behavior analysis

BackgroundAnxiety can seriously impact patients’ psychological and emotional well-being, and sometimes, it can also affect their physical health. Cognitive behavioral analysis is based on cognitive psychology, emphasizing the influence of individual anxiety on emotions and behavior, and is suitable for intervention and treatment of various psychological problems. Therefore, the study uses cognitive behavioral analysis to evaluate the anxiety psychology of participants in prefabricated concrete structure assembly schemes.Subjects and MethodsThe study conducted an EMBase search over the past decade using keywords such as anxiety and psychotherapy to obtain data on alleviating anxiety. Thirty participants in the concrete structure assembly plan were randomly divided into two groups: one group received cognitive behavioral intervention, and the other served as the control group for four weeks. Participants were evaluated for anxiety before and after the experiment using the Self Rating Anxiety Scale (SAS) and the Self Rating Depression Scale (SDS).ResultsThe results showed significant differences in SAS and SDS values between the participants (P<0.05). The group receiving cognitive behavioral intervention showed a significant decrease in SAS and SDS values, while the other group showed no significant changes.ConclusionsParticipants’ anxiety is an essential factor affecting the smooth completion of assembly plans, and timely intervention and treatment are urgently needed. Cognitive behavioral analysis can effectively alleviate participants’ anxiety in prefabricated concrete structure assembly schemes, which is of great significance for the smooth completion of projects.

A system for bioelectronic delivery of treatment directed toward wound healing

The development of wearable bioelectronic systems is a promising approach for optimal delivery of therapeutic treatments. These systems can provide continuous delivery of ions, charged biomolecules, and an electric field for various medical applications. However, rapid prototyping of wearable bioelectronic systems for controlled delivery of specific treatments with a scalable fabrication process is challenging. We present a wearable bioelectronic system comprised of a polydimethylsiloxane (PDMS) device cast in customizable 3D printed molds and a printed circuit board (PCB), which employs commercially available engineering components and tools throughout design and fabrication. The system, featuring solution-filled reservoirs, embedded electrodes, and hydrogel-filled capillary tubing, is assembled modularly. The PDMS and PCB both contain matching through-holes designed to hold metallic contact posts coated with silver epoxy, allowing for mechanical and electrical integration. This assembly scheme allows us to interchange subsystem components, such as various PCB designs and reservoir solutions. We present three PCB designs: a wired version and two battery-powered versions with and without onboard memory. The wired design uses an external voltage controller for device actuation. The battery-powered PCB design uses a microcontroller unit to enable pre-programmed applied voltages and deep sleep mode to prolong battery run time. Finally, the battery-powered PCB with onboard memory is developed to record delivered currents, which enables us to verify treatment dose delivered. To demonstrate the functionality of the platform, the devices are used to deliver H^+ in vivo using mouse models and fluoxetine ex vivo using a simulated wound environment. Immunohistochemistry staining shows an improvement of 35.86% in the M1/M2 ratio of H^+—treated wounds compared with control wounds, indicating the potential of the platform to improve wound healing.

Research on automatic assembly technology of complex curved composite components

Sophisticated composite materials have a range of outstanding broad merits such as high particular strength, high specific stiffness, powerful designability, excellent tiredness resistance, excellent durability, are widely used in transportation, medical, electronics and other area. The assembly process of the composite surface components has large assembly stress, which affects the assembly accuracy. At the same time, the manual assembly cycle is elongated, the efficiency is low, and the quality stability is impoverished, which constraints the assembly mass and assembly power of the complex curved composite components. To improve the assembly power and carry out automatic assembly, this paper designs the automatic assembly technology scheme of the complex curved composite components, designs the automatic assembly scheme verification device, and conducts the automatic assembly test to verify the feasibility of the scheme.

Integrating real-time manufacturing data into a novel serial two-stage adaptive alternate genetic fireworks algorithm for solving stochastic type-II simple assembly line balancing problem

Due to various interference factors, a pre-planned assembly scheme and its cycle time can be disturbed, resulting in the failure of product delivery on schedule. However, when assembly data of the production line can be obtained in real time, the balance of the assembly line could be dynamically adjusted in case of experiencing serious interferences to optimize its cycle time in time and improve its production efficiency. Therefore, this paper proposes a dynamic rebalancing framework by integrating real time manufacturing data into a novel serial two-stage adaptive alternate genetic fireworks algorithm for solving a stochastic type-II simple assembly line balancing problem (SSALBP-II). MES (manufacturing execution system) is used to obtain some real time data such as the resource status, operation information and task information and to judge abnormal phenomenon and the overdue delivery caused by interferences. On this basis, the stochastic type-II simple assembly line balance model is constructed, with a new serial two-stage adaptive alternate genetic fireworks algorithm (STAGFA). This new algorithm can incorporate both genetic algorithm and fireworks algorithm to solve the model according to the transformation of population diversity discrimination index. Through the comparison between STAGFA and other algorithms such as fireworks algorithm, genetic algorithm, other improved intelligent algorithms, it is proved that the STAGFA is effective and superior in solving the assembly line (re)balance problem. Then, the rebalanced scheme verified by simulation is dispatched to control the physical assembly line and realize dynamic rebalancing cycle time effectively.

Design and Simulation of On-Orbit Assembly System Based on Insect-Inspired Transportation

In response to the requirements of large-scale space in-orbit assembly and the special environment of low gravity in space, this paper proposes a small robot structure with the integration of assembly, connection, and vibration reduction functionalities. Each robot consists of a body and three composite mechanical arms-legs, which can dock and transfer assembly units with the transport spacecraft unit, and also crawl along the edge truss of the assembly unit to a designated location to complete in-orbit assembly while ensuring precision. A theoretical model of robot motion was established for simulation studies, and in the research process, the vibration of the assembly unit was studied, and preliminary adjustments were made to address the vibration issue. The results show that this structure is feasible for in-orbit assembly schemes and has good adjustment ability for flexible vibration.

Static and Dynamic Magnetic Pull in Modular Spoke-Type Permanent Magnet Motors

This work studied the static magnetic pull of a modular spoke-type permanent magnet motor (MSTPMM) with no rotor eccentricity during the motor’s final assembly process and its dynamic magnetic pull during different motor operating states. A new final assembly scheme was proposed to significantly reduce the static magnetic pull during the final assembly process of the motor. The methods required to reduce the unbalanced radial magnetic pull of the whole stator, which is caused by partial stator module operation, were also studied. Firstly, the structure of the MSTPMM was examined. The static magnetic pull that occurred with the implementation of the two motor final assembly methods was studied in order to prove the effectiveness of reducing the maximum static magnetic pull. Moreover, the maximum magnetic pull during the assembly process was also observed. Then, the dynamic magnetic pull was studied with different motor operating states: no load, on load, and partial stator module operation. To solve the unbalanced radial magnetic pull of the whole stator, which is caused by partial stator module operation, methods of changing the angle between the stator current vector and the q axis (Ψ) or the d axis current (id) were also studied.

Experimental studies of reciprocating liquid immersion cooling for 18650 lithium-ion battery under fast charging conditions

In this study, the reciprocating liquid immersion cooling has been proposed and tested for cooling the cylindrical lithium-ion battery (LIB) under fast charging conditions. First, the temperature responses of LIB under fast charging conditions with liquid immersion cooling and natural convection are compared. Experimental results show that the reciprocating liquid immersion cooling possesses better heat dissipation performance than natural convection, not only can precisely control the cell temperature to around 50 °C during fast charging, but also can improve the cell temperature uniformity. Meanwhile, the reciprocating system enables rapid cooling of the battery during the resting process, which consequently achieves asymmetric control of high-temperature charging and room temperature discharging. Then, the effects of different charging rates and different charging protocols are explored, and the high-speed photography is used to observe and record the liquid-gas phase transition phenomenon under three different charging rates. Finally, the temperature response and energy consumption analysis of LIB in the fast-charging process with three different assembly schemes are investigated. This study provides preliminary proof for the advantage of applying liquid immersion cooling for LIB under fast charging.

Seismic Behavior of Precast Bridge Column–Cap Beam Joints with Grouted Corrugated Duct Connections: Experimental and Numerical Study

This paper presented an assembly scheme that was based on bundled bars–grouted corrugated duct connections. The scheme was used for the connection between the bridge column with bundled bars and the cap beam in an elevated subway station. Two 1/3-scale bridge column–cap beam joint specimens were designed and fabricated to verify the scheme. The test specimens included a precast assembly specimen and a cast-in-place (CIP) specimen. Pseudostatic cyclic loading tests were performed to investigate the flexural capacity, failure mode, and hysteretic behavior of the CIP and precast assembly specimens. The test results showed that: (1) the flexural capacity of the precast assembly specimen was close to that of the CIP specimen; (2) the energy dissipation capacity of the precast assembly specimen was weaker compared with that of the CIP specimen; and (3) the assembly scheme that was based on bundled bars–grouted corrugated duct connections was reliable. Finally, the finite-element model for the test specimens was established by calling the PQ-FIBER user subroutine developed by Tsinghua University with ABAQUS to study the seismic performance of the test specimens. Compared with the test results, the finite-element models could simulate the failure mode and hysteretic behavior of the reinforced-concrete specimens.