Mechanical Reliability and Design

PurposeThe generic design environment for a flexible printed‐circuit board assemblies (PCBA) remanufacturing cell contains four interrelated complex design domains. Mechanical design domains are really complex and the use of well‐proven mechanical product design methodologies does not help the designer. Hence, this paper aims to develop a generic systematic design methodology for a flexible PCBA remanufacturing cell.Design/methodology/approachThe study investigates the use of conventional mechanical product design techniques for the design of a flexible PCBA rework (remanufacturing) cell. It indicates problems and the weaknesses when conventional product design techniques are used for the development of flexible manufacturing systems (FMS). It then provides a new systematic mechanical design methodology for designing a flexible PCBA rework (remanufacturing) cell. The design methodology is intended to be generic in order to apply successfully to any FMS design.FindingsConventional product design methodology cannot be used directly for the design of a flexible PCBA remanufacturing cell. Hence, two design methodologies were developed: the generic FMS mechanical design methodology and a specific FMS design methodology for a PCBA rework cell. The first one was developed based on the tasks of the conventional product design process integrated with new design tools. The generic design methodology was then extended to obtain the second methodology for a PCBA rework cell design. Both of the methodologies were applied to a flexible PCBA rework cell design problem. Both design methodologies eliminated unusable design solutions at the early design stages of the conceptual design process and made the design process easier.Practical implicationsThe generic and specific design methodologies provide a better design environment, even for less specialized FMS designers.Originality/valueThe design methodologies may help for the commercialization of a flexible PCBA remanufacturing cell that may be used for SM rework and assembly.

Lipid nanoparticles for mRNA delivery and gene editing have the potential to transform the current therapeutic landscape. Nonetheless, a major bottleneck using this technology is the difficulty in achieving cell- and tissue-specific delivery and avoiding liver accumulation. Here we report the rational design of peptide ionizable lipids to assemble lipid nanoparticles with organ-selective mRNA delivery. Structure-activity and structure-selectivity relationship analyses enable us to obtain a general and predictable strategy for peptide ionizable lipid design. By incorporating artificial ionizable and natural amino acids and/or functional molecules into peptide ionizable lipids, we create lipid nanoparticles with tissue-specific targeting, including the lungs, liver, spleen, thymus and bone. In particular, lipid nanoparticles containing peptide lipids targeting the liver show comparable efficacy and safety compared with FDA-approved formulations. Furthermore, lipid nanoparticles with peptide lipids achieve the efficient co-delivery of PEmax mRNA and engineered prime editing guide RNA for prime editing of the liver and lungs. Overall, our platform offers a predictable methodology for the rational design of tissue-targeting lipid nanoparticles that might aid the development of improved mRNA-based gene editing therapeutics.

With the complexity of mechanical manufacturing system design increasing, the traditional single-objective optimization method can no longer meet the needs of multi-objective optimization, such as lightweight, high efficiency, low energy consumption and long life. Multi-objective optimization algorithm is widely used in mechanical design and manufacturing process planning because of its good convergence and diversity. Taking robot motion planning as an example, this paper analyzes the application methods of multi-objective optimization algorithm in mechanical structure design in detail, including problem description, multi-objective optimization model construction, algorithm application and performance analysis. Through the application of Genetic Algorithm (GA), this paper shows how the multi-objective optimization algorithm can balance multiple objectives such as path length, energy consumption and obstacle avoidance effect, and realize more intelligent and efficient solutions in robot motion planning. Performance analysis shows that GA is superior to single-objective optimization and random search algorithm in optimization effect, computational efficiency and stability. In addition, this paper also discusses the influence of the change of target weight and algorithm parameters on the optimization results, which provides valuable reference for future algorithm optimization and practical application. Multi-objective optimization algorithm shows obvious advantages in mechanical manufacturing system, which provides new ideas and methods for realizing more efficient, more environmentally friendly and more intelligent mechanical manufacturing design.

314 stainless steel (314 SS) is an austenitic alloy of stainless steel which adheres to the linear-elastic model of material behavior. It is used in high-temperature environments, as well as several ballistic and aerospace applications. When 314 stainless steel is deformed past its elastic limit, its molecular structure is stressed in a way that strengthens the areas of the steel local to the deformed material. This process is called "work hardening," or "cold working." As materials are cold worked, properties such as ultimate tensile strength, yield stress, and hardness will change proportional to the degree of cold working. For the design of ballistics and aerospace structures, a working knowledge of these fundamental properties for 314 SS is vital. Despite this need little work has been reported on the material properties of work hardened 314 stainless steel in literature. The research conducted herein aims to characterize the behavior of 314 SS tubing which has been work hardened to various degrees. The stainless steel tubing chosen was of a 3/8 inch outer diameter and 1/8 inch outer diameter. This small diameter geometry was the best replication of the aforementioned application of this material in the aerospace industry. To work harden the tubing, the tubes were bent at 5° intervals, ranging from 5 to 15°, and then bent back to their original position. Some samples were further work hardened by repeated bending to the same degree interval. The effects of the cold work on the material properties were quantified using a tensile test, a microhardness test, and resonant ultrasound spectroscopy. The results of the experiment showed that the yield strength of the part increases with small angle bends such as 5 degrees and further increases with repeated bending. Bending beyond this 5° point appeared to produce a negative effect on the yield strength of the part. The change in yield strength between any set of trials was typically around 1–2%. The ultimate strength consistently decreased with increased work hardening, approaching 2–3% decreases with greater amounts of work hardening. The change due to repeated bending was on average less than 1%. The analysis of the failure strength was inconclusive, with the failure strength varying by as much as 19% from the control. It is likely that more trials would reveal a clear pattern, indicating what effect the work hardening has, if any, on the failure strength.

Activatable second near‐infrared window (NIR‐II; 1.0–1.7 µm) fluorescence probes that uncage deep‐tissue penetrating fluorescence by disease‐related biomarker stimuli hold great promise for detecting diseases with a poor understanding of the pathology at the molecular level with unprecedented resolution. However, currently, very few activatable NIR‐II fluorescence probes are reported mainly due to the lack of a simple yet general design strategy. Herein, a new and fairly generic design strategy using a bio‐erasable intermolecular donor–acceptor interaction to construct activatable NIR‐II fluorescence probes is reported. An organic semiconducting nanoprobe (SPNP) is constructed through blending a biomarker‐sensitive organic semiconducting non‐fullerene acceptor (3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐cyclopentane‐1,3‐dione‐[c]thiophen))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2',3'‐d']‐s‐indaceno[1,2‐b:5,6‐b'] dithiophene) (ITTC) (one of electric acceptors in organic solar cells) with a biomarker‐inert semiconducting polymer donor 5‐(4,8‐bis((2‐ethylhexyl)oxy)‐6‐methylbenzo[1,2‐b:4,5‐b']difuran‐2‐yl)‐10‐methylnaphtho[1,2‐c:5,6‐c']bis([1,2,5]thiadiazole) (PDF) in an amphiphilic‐polymer‐coated single nanoparticle to suppress NIR‐II fluorescence of the donor via a intermolecular donor–acceptor interaction. The acceptor ITTC is found to be specifically degraded by hypochlorite (an important biomarker) to erase its acceptor property, thus erasing the intermolecular donor–acceptor interaction and uncaging NIR‐II fluorescence. Consequently, SPNP exhibits a 17.5‐fold higher fluorescence brightness in the hypochlorite‐abnormal inflammation in vivo than in normal tissues. Our bio‐erasable intermolecular donor–acceptor interaction strategy provides simple yet general guidelines to design various biomarker‐activatable NIR‐II fluorescence probes.

Panoramic stereo images, captured by distributed devices then mosaicking, are competent contents for virtual reality applications. Mosaicking raw images with different perspectives into satisfying final results is still not efficient enough, even if state-of-the-art algorithms are employed. For improving this efficiency in optical methods, we delve into the potential of the capturing system. Two parallax factors, peak parallax and deviation of parallaxes, are proposed to assess the mosaicking capability. By controlling variables and numerical computation, rules between parallax factors and design parameters have been revealed. Validation by simulations, large capturing distance, more cameras, compact arrangement, and moderate overlaps are suggested as the general design strategy. Benefiting from efficient mosaicking, systems based on our design strategy would have potential for real-time applications.

Mechanical, materials, and biological causes of intracortical probe failure have hampered their utility in basic science and clinical applications. By anticipating causes of failure, we can design a system that will prevent the known causes of failure. The neural probe design was centered around a bio-inspired, mechanically-softening polymer nanocomposite. The polymer nanocomposite was functionalized with recording microelectrodes using a microfabrication process designed for chemical and thermal process compatibility. A custom package based upon a ribbon cable, printed circuit board, and a 3D-printed housing was designed to enable connection to external electronics. Probes were implanted into the primary motor cortex of Sprague-Dawley rats for 16 weeks, during which regular recording and electrochemical impedance spectroscopy measurement sessions took place. The implanted mechanically-softening probes had stable electrochemical impedance spectra across the 16 weeks and single units were recorded out to 16 weeks. The demonstration of chronic neural recording with the mechanically-softening probe suggests that probe architecture, custom package, and general design strategy are appropriate for long-term studies in rodents.

Isotropic pairwise interactions that promote the self-assembly of complex particle morphologies have been discovered by inverse design strategies derived from the molecular coarse-graining literature. While such approaches provide an avenue to reproduce structural correlations, thermodynamic quantities such as the pressure have typically not been considered in self-assembly applications. In this work, we demonstrate that relative entropy optimization can be used to discover potentials that self-assemble into targeted cluster morphologies with a prescribed pressure when the iterative simulations are performed in the isothermal-isobaric ensemble. The benefits of this approach are twofold. First, the structure and the thermodynamics associated with the optimized interaction can be controlled simultaneously. Second, by varying the pressure in the optimization, a family of interparticle potentials that all self-assemble the same structure can be systematically discovered, allowing for a deeper understanding of self-assembly of a given target structure and providing multiple assembly routes for its realization. Selecting an appropriate simulation ensemble to control the thermodynamic properties of interest is a general design strategy that could also be used to discover interaction potentials that self-assemble structures having, for example, a specified chemical potential.

The mechanical reliability design method is a common method, and it is the most direct and effective method to carry out the mechanical reliability design at present. The reliability optimization design is an effective optimization design method which is developed in combination with the reliability design theory on the basis of the conventional optimization design. Taking the antifriction bearing as an example, this paper systematically expounds all kinds of mechanical reliability design methods. Through comprehensive analysis of various factors that affect the reliability of colliery machine, the index system of colliery machine reliability evaluation is established. Because of the complexity and diversity of the use of colliery machine in the evaluation system, and the fuzziness of human thinking, it is difficult to give the deterministic evaluation information in numerical form, so this paper also analyzes the design method of colliery mechanical reliability, and puts forward an interval fuzzy evaluation method for colliery mechanical reliability evaluation to avoid overload operation of colliery machine and ensure safety production and safety of workers. The simulation results show that the inherent law of reliability is effectively characterized by this method, and it provides a evidence for security produce and scientific decision-making of colliery mechine.

Yield strength and work hardening are two critical mechanical properties of metallic structural materials. However, increasing yield strength through conventional strengthening mechanisms often restricts further dislocation multiplications and interactions, which significantly reduces work hardening and poses a challenge to achieving an optimal balance between these properties in material design. Here, an innovative approach to simultaneously enhance both yield strength and work hardening in a heterostructured, nanoprecipitation‐strengthened alloy is reported. This alloy exhibits an exceptional combination of a yield strength exceeding 1.5 GPa and an ultrahigh work hardening rate of 6 GPa, resulting in an extremely high tensile strength of 2.2 GPa and a uniform ductility of 20%. The ultrahigh yield strength primarily stems from nanoprecipitates and ultrafine grains, while the exceptional work hardening mainly originates from hetero‐interface‐mediated twinning. The hetero‐deformation between the coarse‐grained and ultrafine‐grained regions results in dislocation pile‐ups and strain gradients near the interfaces, which provides the ultrahigh stress necessary to activate mechanical twinning, thereby substantially improving the work hardening and plastic deformation stability of the alloy. The hetero‐interface architecting strategy can potentially be applied to numerous other alloys, paving the way for designing novel materials with unprecedented mechanical properties for technological applications.

Intraparticle protein diffusion effect on gradient elution chromatography

The water clocks of the 12th-century Islamic scientist Ismail Al-Jazari may be regarded as among the most outstanding engineering masterpieces in the history of science and technology in Persia. His other works testify to his remarkable ability in design methodology and in different aspects of mechanical engineering design and manufacture such as robotics, fluid mechanics, strength of materials, and statics. In this study in experimental archaeology two of his water clocks – namely the dragon clock and the peacock clock – were considered for the purposes of making working reconstructions. The historical background, design details, and a technical and comparative analysis of these inventions are presented here. Replicas were constructed in accordance with the indications provided in Al-Jazari’s A Compendium on the Theory and Practice of the Mechanical Arts and tests have shown that both clocks operated exactly as described in his book, and with an acceptable degree of precision.

The ideas of the sharing economy have facilitated innovative business applications, such as Uber and Airbnb. As an example of a sharing economy application, ridesharing services take advantage of underutilized resources to create economic value. However, the unruly design of ridesharing systems may make urban traffic more congested and cause other technology-organization-environment issues. This study explores the application of blockchain and smart contract technologies to enhance ridesharing services by harvesting the blockchain benefits of transaction traceability, process transparency, system automation and disintermediation. After presenting system design and implementation details for building and deploying a blockchain-based system to support the reengineered ridesharing service with required business functions, we conduct functionality/performance tests and theory-based comparative analysis to confirm its feasibility and applicability. The results reveal that our system with blockchain-enabled benefits is superior to incumbent ridesharing systems. Moreover, while prior research rarely reports the design and implementation details of blockchain-based systems to support sharing economy services, this paper primarily contributes to extant literature by not only proposing a layered system architecture adapting blockchain and smart contracts into the desired ridesharing service but also demonstrating the design and implementation details, covering the development tools, the deployment environment and the deployed smart contracts.

Detailed parametric design methodology for hydrodynamics of liquid–solid circulating fluidized bed using design of experiments

Conical worm gearing is a new type of worm gearing composed of a conical worm and a conical worm wheel, which differs from ordinary cylindrical worm gearing in that the working helical surface of the worm in the conical worm gearing pair is offset on the side of the worm wheel, and the shape of the worm and the worm wheel are conical. Taking the Archimedean cone-worm transmission as the research object, using the principle of gear meshing, the tooth equations of the cone worm and cone worm gear are deduced, combining with MATLAB, Solidworks and other computer-aided software for solid modeling of the cone-worm transmission, to obtain the three-dimensional model and the model is assembled and then analyzed by the finite element software to find out that the contact and force conditions of the cone-worm transmission meet the actual requirements, which is a good idea for the design and reliability of miniature transmission mechanism. It provides theoretical support for the design and reliability of micro transmission mechanism.