Flexible Matrix Research Articles

Transfer-printing a surface-truncated photonic crystal for multifunction-integrated photovoltaic window

Precise light manipulation is of paramount importance in improving the performance of semi-transparent organic photovoltaics (STOPVs) for their orientation toward building-integrated photovoltaic window. Nevertheless, one critically important issue for the integration of optical modulation with STOPV devices, lies in the damage from the harsh direct deposition steps to the intrinsic properties and long-term durability of STOPVs. Here a transfer-printing (TP) approach, in which photonic crystals (PC) films are deposited onto a self-adhesive and flexible matrix for their integration with STOPV devices, was first reported, enabling the resultant TPPC-STOPV devices with superior optical-related multifunction. In contrast to these devices based on direct-evaporated PC film, the non-encapsulated TPPC-STOPVs present an ultraviolet blocking (UVB) as high as 96%, an infrared rejection (IRR) of 92%, an enhanced power conversion efficiency (PCE) by 5% as well as superior long-term durability as 96% of its initial PCE. Their gifted superior UVB and IRR properties are individually on a par with those of the stat-of-the-art commercial optical films for smart solar window. This transfer-printing approach makes it possible to separate the high-energy fabrication of high-quality contacts from target optoelectronic devices, providing a wide range of possibilities for the integration of high-quality contacts with optoelectronic devices, including organic, silicon and perovskite optoelectronic devices, as well as their large-area flexible integration.

Self-assembling bilayer wiring with highly conductive liquid metal and insulative ion gel layers

Ga-based liquid metals (LMs) are expected to be suitable for wiring highly deformable devices because of their high electrical conductivity and stable resistance to extreme deformation. Injection and printed wiring, and wiring using LM–polymer composites are the most popular LM wiring approaches. However, additional processing is required to package the wiring after LM patterning, branch and interrupt wiring shape, and ensure adequate conductivity, which results in unnecessary wiring shape changes and increased complexity of the wiring methods. In this study, we propose an LM–polymer composite comprising LM particles and ion gel as a flexible matrix material with low viscosity and specific gravity before curing. Moreover, the casting method is used for wire patterning, and the material is cured at room temperature to ensure that the upper insulative layer of the ion gel self-assembles simultaneously with the formation of LM wiring in the lower layer. High conductivity and low resistance change rate of the formed wiring during deformation are achieved without an activation process. This ion gel–LM bilayer wiring can be used for three-dimensional wiring by stacking. Furthermore, circuits fabricated using ion gel–LM bilayer wiring exhibit stable operation. Therefore, the proposed method can significantly promote the development of flexible electronic devices.

Quadrilateral element in mixed FEM for analysis of thin shells of revolution

The purpose of study is to develop an algorithm for the analysis of thin shells of revolution based on the hybrid formulation of finite element method in two dimensions using a quadrilateral fragment of the middle surface as a discretization element. Nodal axial forces and moments, as well as components of the nodal displacement vector were selected as unknown variables. The number of unknowns in each node of the four-node discretization element reaches nine: six force variables and three kinematic variables. To obtain the flexibility matrix and the nodal forces vector, a modified Reissner functional was used, in which the total specific work of stresses is represented by the specific work of membrane forces and bending moments of the middle surface on its membrane and bending strains, and the specific additional work is determined by the specific work of membrane forces and bending moments of the middle surface. Bilinear shape functions of local coordinates were used as approximating expressions for both force and displacement unknowns. The dimensions of the flexibility matrix of the four-node discretization element were found to be 36×36. The solution of benchmark problem of analyzing a truncated ellipsoid of revolution loaded with internal pressure showed sufficient accuracy in calculating the strength parameters of the studied shell.

Design and Characterization of Non-Erosive Polymeric Tooth-Whitening Compositions

We investigated the physical properties and tooth-whitening effect of polymeric tooth-whitening compositions based on orally acceptable polymers, polyvinyl acetate (PVAc), ethyl cellulose (EC), and polyvinyl pyrrolidone. The tooth-whitening composition was prepared with hydrogen peroxide (H2O2) as a tooth-bleaching agent and an orally acceptable polymer through simple mixing and stirring in ethyl alcohol. PVAc and EC polymers showed non-erosive features and sustainable polymeric matrices in a similar oral environment. In particular, non-erosive PVAc polymer exhibited excellent adhesive and flexible film matrix on bovine teeth. PVAc-H2O2 tooth-whitening composition presented a residual H2O2 and an overall color change value (ΔE*) of 26.5% and 16.54%, respectively. The non-erosive polymeric composition is expected to improve tooth-whitening efficacy in various oral products.

A novel phase change composite with ultrahigh through-plane thermal conductivity and adjustable flexibility

With the rapid development of micro-nano electronics, thermally conductive materials with remarkable through-plane thermal conductivity (κ⊥) and great flexibility are greatly urgent to effective thermal management. The fillers with high thermal conductivity (TC) are commonly assembled to achieve this target. However, the imperfect contact between the joint fillers will lead to high thermal resistance (R), hindering thermal transport. Herein, we fabricated thermal interface materials (TIMs) with ultra-high κ⊥ (up to 168.4 W m−1 K−1) and adjustable flexibility by the combination of highly thermally conductive carbon fiber bundles (CF) and polymer encapsulated phase change materials (PCMs). The alignment of consecutive CF guarantees the continuity of thermal paths, greatly facilitating thermal transport. While the slantly slicing technique and softening effect of PCMs beyond phase transition temperature lead to an attenuated compression stress (1.6 MPa@10% strain with a CF loading of 50 wt%). What’s more, the latent heat absorbed by PCMs is also conducive to thermal management. Thus, during a CPU temperature-control experiment, the application of as-prepared TIMs manifests a temperature decline of 33.9 °C of CPU. This work opens a new perspective to fabricating TIMs with ultrahigh κ⊥ and low compression stress (σ) by the combination of thermally induced flexible matrix and the slantly slicing technique of aligned CFs.

Self-healing, EMI shielding, and antibacterial properties of recyclable cellulose liquid metal hydrogel sensor

Flexible hydrogels are promising materials for the preparation of artificial intelligence electronics and wearable devices. Introducing a rigid conductive material into the hydrogels can improve their electrical conductivities. However, it may have poor interfacial compatibility with the flexible hydrogel matrix. Therefore, we prepared a hydrogel containing flexible and highly ductile liquid metal (LM). The hydrogel can be used as a strain sensor to monitor human motion. The hydrogel showed many properties (i.e., recyclability, EMI shielding properties (33.14 dB), antibacterial (100 %), strain sensitivity (gauge factor = 2.92), and self-healing) that cannot be achieved simultaneously by a single hydrogel. Furthermore, the recycling of LM and their application to hydrogel-based EMI shielding materials have not been investigated previously. Due to its excellent properties, the prepared flexible hydrogel has great potential for applications in artificial intelligence, personal healthcare, and wearable devices.

Macro–microscale topological design for compliant mechanisms with special mechanical properties

This paper proposes a macro–microscale topology optimization approach for constructing compliant mechanisms with deterministic mechanical characteristics based on the essential properties of structural materials. The topology optimization process is divided into two scales: in macroscale optimization, the flexibility matrix factor is used as the constraint function, and the Augmented Lagrangian method is used to transform the constrained optimization problem into an unconstrained model, and the free materials optimization approach is used to generate a compliant mechanism with multiple material attribute elements at the macroscale. In microscale optimization, each microstructures are optimized to obtain special mechanical properties issued from macroscale optimized results. Within the allowable elastic deformation range, the compliant mechanism with arbitrary mechanical properties can be designed, and several numerical examples demonstrate that the compliant mechanisms have expected motion characteristics. The proposed method solved the quantitative design of mechanical properties of compliant mechanisms and can be extended to other fields of compliant mechanisms using macro–microscale topology optimization.

PENGUKURAN KINERJA RANTAI PASOK TEMBAKAU PADA BAGIAN HULU DI PR. X MALANG

<p><em>Activities in the supply chain have problems related to uncertainty, to be faced in this condition the business actors need to know their performance and improve their performance. The level of best or bad performances of a company has based on the application of supply chain management in managing the business activities. The implementation of supply chain management is faced with a problem such as uncertainty of market conditions about price and quantity of supply and demand that can affect the operational activities of the supply chain. The supply chain problem also occurs in the tobacco supply chain as the plantation commodity with high economic value and the seasonal characteristic. The upstream side of the tobacco supply chain is needed to determine the performance that has been achieved. Therefore, research on the performance measurement of upstream tobacco supply chain at PR. X Malang is important. The purposes of this study are to describe the mechanism of implementation of tobacco supply chain management on the upstream side, and analyzing the performance of the upstream of the tobacco supply chain, and formulate a strategy to improve the upstream of supply chain performance. The analysis used in this study is based on the SCOR model with five core processes (plan, source, make, deliver, return) and five performance attributes (reliability, responsiveness, agility, cost, asset). This study uses 3 key informants consisting of farmers, collectors, and manufacturers with purposive techniques. The result of this study shows that the farmer performance needs an improvement based on the flexibility and TSCC</em><em> (total supply chain cost)</em><em> matrix performance, the collector performance needs an improvement based on TSCC performance matrix and manufacture performance needs an improvement based on the flexibility and TSCC matrix performance.</em></p>

Engineering Matrix Materials for Composites: Their Variety, Scope and Applications

Matrices are essentially binders for the reinforcements of composite material. Appropriate selection of fine chemicals is vital for the creation of desired matrices for generating composite materials. In fact, matrix is a subclass of a composite material. Matrices are generally of four kinds such as (i) polymer (hard as well as flexible), (ii) metal, (iii) ceramic, and (iv) cement. Each type of these subclasses of the matrix is discussed with a brief of their pros and cons. Polymer matrices are generally organic based whereas metal or ceramic matrices are inorganic in nature. Hard plastic matrix as well as flexible rubbery matrix are also discussed in the light of their applications. Carbon as matrix material for hi-tech C/C (carbon/carbon) composite materials is also stated. Cement is a special kind of inorganic matrix material because of its very special solidification mechanism during the formation of concrete composite; and it carries bulk values in the engineering area. For higher temperatures, carbon, ceramic or metal matrix materials are useful. Ceramics possess various conductivities, but they have poor tensile strength despite their ability to afford high-temperature products. Generally lightweight metals such as titanium, aluminum, magnesium, and intermetallics such as Ni-aluminide and Ti-aluminide are used; and the operating temperature can be extended to 2000 °C. The advantages of metal matrices are higher strength and ductility than those of polymers. Carbon matrix based carbon/carbon (C/C) composites can be used even at the temperature of ~3000 °C, but are preferred only in critical engineering areas of applications. Different types of matrix material may also prove to be efficacious constituent item for innovative design of integrated structure in the ever challenging area of Blast and penetration resistant materials (BPRM).

Vertical performance of rock-socketed pile group in layered saturated rock-soil mass

This paper studies the vertical performance of rock-socketed pile group embedded in layered saturated rock-soil mass. The three-node bar element is utilized to discretize the pile, and the global stiffness matrix equation of rock-socketed pile group is assembled by the finite element method. Based on the solution for the interaction between a rock-socketed single pile and rock-soil mass, the flexibility matrix equation of rock-soil mass for the pile group is derived by the boundary element method. Combination of the force balance and displacement compatibility conditions for the rigid pile cap leads to the solution of rock-socketed pile group embedded in saturated rock-soil mass. The correctness of the proposed method is examined by comparing the solutions predicted by the present paper with the solutions from existing literature and ABAQUS results. The relevant factors affecting the vertical performance of rock-socketed pile group, such as the socketed length, pile spacing, pile-rock mass modulus ratio, length-diameter ratio and the rock mass stratification, are further discussed

A Fast Calculation Method for Sensitivity Analysis Using Matrix Decomposition Technique

The sensitivity reanalysis technique is an important tool for selecting the search direction in structural optimization design. Based on the decomposition perturbation of the flexibility matrix, a fast and exact structural displacement sensitivity reanalysis method is proposed in this work. For this purpose, the direct formulas for computing the first-order and second-order sensitivities of structural displacements are derived. The algorithm can be applied to a variety of the modifications in optimal design, including the low-rank modifications, high-rank modifications, small modifications and large modifications. Two numerical examples are given to verify the effectiveness of the proposed approach. The results show that the presented algorithm is exact and effective. Compared with the existing two reanalysis methods, this method has obvious advantages in calculation accuracy and efficiency. This new algorithm is very useful for calculating displacement sensitivity in engineering problems such as structure optimization, model correction and defect detection.

Monolithically printed all-organic flexible photosensor active matrix

Upcoming technologies in the fields of flexible electronics require the cost-efficient fabrication of complex circuitry in a streamlined process. Digital printing techniques such as inkjet printing can enable such applications thanks to their inherent freedom of design permitting the mask-free deposition of multilayer optoelectronic devices without the need for subtracting techniques. Here we present an active matrix sensor array comprised of 100 inkjet-printed organic thin film transistors (OTFTs) and organic photodiodes (OPDs) monolithically integrated onto the same ultrathin substrate. Both the OTFTs and OPDs exhibited high-fabrication yield and state-of-the-art performance after the integration process. By scaling of the OPDs, we achieved integrated pixels with power consumptions down to 50 nW at one of the highest sensitivities reported to date for an all-organic integrated sensor. Finally, we demonstrated the application potential of the active matrix by static and dynamic spatial sensing of optical signals.

A Sensitive and Flexible Poroelastic Barium Titanate Matrix for Pressure Sensing Applications

This letter reports on poroelastic barium titanate matrix (PBM) for flexible pressure sensor applications. The fabrication of PBM is a simple and cost-effective process that allows an optimized composition of polydimethylsiloxane (PDMS) and barium titanate (BTO) to penetrate through the sugar template via capillary action. The fabricated PBM undergoes large deformation if compared to the state-of-the-art pressure sensors. Around a two-fold increase in sensitivity is observed with the appropriate weight percent (%) of BTO in PDMS and the %porosity in the PBM structure. The PBM generates a peak voltage of ∼1.1 V, whereas the nonporous composite (BTO+PDMS) generates only ∼500 mV. The response of PBM is highly linear (coefficient of linearity 0.983) and repeatable with a deviation of 0.47%. Furthermore, the operating range of PBM is 5–100 kPa. Finite element simulations are carried out to find the relation between the substrate porosity, %weight ratio of BTO, and the generated voltage. The optimized PBM can be exploited for applications, such as gait biomechanics.

Vibration and wave propagation in functionally graded beams with inclined cracks

This paper proposes an FEA method to study the vibration and wave propagation in functionally graded material (FGM) beams with multiple inclined cracks by introducing the local flexibility matrix caused by the cracks. The bending and tensile stiffnesses of the inclined cracks and their interaction are taken into consideration. Two-node (three degrees of freedom per node) beam element is used. The inclined cracks are equivalent to transversal cracks to calculate the additional flexibility matrix of the inclined cracked FGM beam element. The material properties of the FGM beam are supposed to satisfy the exponential law along its thickness. The governing equations of motion for the FGM beam with multiple inclined cracks are deduced in the frame of Euler-Bernoulli theory and Lagrange function, and numerically solved by the Newmark average acceleration method. Both theoretical and numerical comparisons are presented to validate the present method for the inclined cracked FGM beam with varying boundary conditions, arbitrary inclined crack angles as well as varying inclined crack lengths. The effects of the location, length, inclined angle and number of the inclined cracks as well as material property ratio on the fundamental frequencies and wave propagation characteristics of the inclined cracked cantilever FGM beams are comprehensively investigated.

Design of Incidence Matrices With Limited Constellation Expansion in Massive Connectivity NOMA Systems

Non-orthogonal multiple-access (NOMA) is designed to transmit massive amounts of user communications. The incidence matrix manages the relationship between users and resources. This study focused on increasing user supportability and complexity reduction using larger incidence matrices. Our approach to optimizing the incidence matrix to improve system capacity and reduce complexity is based on two critical mathematical concepts: Parallel classes in hypergraph theory and combinatorial designs allow us to explore and extend incidence matrices. Frame theory is used to estimate matrix structures. Then, we investigate applications utilizing our incidence matrix designs–Simple Orthogonal Multi-Arrays (SOMA). The characteristics of SOMA reflect the unique Latin Square pattern, allowing us to produce a highly flexible and fair resource allocation matrix. SOMA designs let us support overload factors over 500%. The theoretical performance analysis equations of our NOMA system were established to support dynamic adaptability and optimization. We implemented and evaluated security methods for eavesdroppers. The prototype of the user hierarchy allows a higher-priority group to have a lower error rate without significantly affecting the system’s performance. Finally, the Monte Carlo simulation indicated that our NOMA systems allow higher degrees of freedom and lower complexity than other NOMA schemes while maintaining graceful error rates with a maximum 33% improvement.

Research status of polysiloxane-based piezoresistive flexible human electronic sensors.

Flexible human body electronic sensor is a multifunctional electronic device with flexibility, extensibility, and responsiveness. Piezoresistive flexible human body electronic sensor has attracted the extensive attention of researchers because of its simple preparation process, high detection sensitivity, wide detection range, and low power consumption. However, the wearability and affinity to the human body of traditional flexible human electronic sensors are poor, while polysiloxane materials can be mixed with other electronic materials and have good affinity toward the human body. Therefore, polysiloxane materials have become the first choice of flexible matrixes. In this study, the research progress and preparation methods of piezoresistive flexible human electronic sensors based on polysiloxane materials in recent years are summarized, the challenges faced in the development of piezoresistive flexible human electronic sensors are analyzed, and the future research directions are prospected.

Damage Identification under Incomplete Mode Shape Data Using Optimization Technique Based on Generalized Flexibility Matrix

Damage Identification under Incomplete Mode Shape Data Using Optimization Technique Based on Generalized Flexibility Matrix

Effects of Co-Solvent-Induced Self-Assembled Graphene-PVDF Composite Film on Piezoelectric Application

A persistent purpose for self-powered and wearable electronic devices is the fabrication of graphene-PVDF piezoelectric nanogenerators with various co-solvents that could provide enhanced levels of durability and stability while generating a higher output. This study resulted in a piezoelectric nanogenerator based on a composite film composed of graphene, and poly (vinylidene fluoride) (PVDF) as a flexible polymer matrix that delivers high performance, flexibility, and cost-effectiveness. By adjusting the co-solvent in the solution, a graphene-PVDF piezoelectric nanogenerator can be created (acetone, THF, water, and EtOH). The solution becomes less viscous and is more diluted the more significant the concentration of co-solvents, such as acetone, THF, and EtOH. Additionally, when the density is low, the thickness will be thinner. The final film thickness for all is ~25 µm. Furthermore, the- crystal phase becomes more apparent when graphene is added and combined with the four co-solvents. Based on the XRD results, the peak changes to the right, which can be inferred to be more dominant with the β-phase. THF is the co-solvent with the highest piezoelectric output among other co-solvents. Most of the output voltages produced are 0.071 V and are more significant than the rest.

Surface engineered hollow Ni-Co-P@TiO2-x nanopolyhedrons as high performance anode material for sodium storage

With the proposal of carbon peaking and carbon neutrality goals, clean energy storage is attracting more and more attentions. In view of the lack of lithium resource in our earth, sodium-ion batteries are considered as the emerging and promising next-generation energy storage devices. Appropriate high-performance anode materials play a vital role in the development of sodium-ion batteries. Here, a core-shell hollow Ni-Co-P nanopolyhedron interconnected by oxygen defect TiO2 (Ni-Co-P@TiO2-x) is reported, which is synthesized by ion etching-hydrolysis and subsequent phosphatization/hydrogenation treatment using ZIF-67 as template and hybrid carbon source. The achieved Ni-Co-P@TiO2-x material has several distinct advantages including hollow core-shell structure, flexible conductive carbon matrix, stable electroactive coating layer, and efficient pseudocapacitive behavior, resulting in high reversible capacities, remarkable rate capability and excellent cycle stability. The synergetic battery-capacitor characteristic of Ni-Co-P@TiO2-x material makes it become a promising anode for sodium-ion batteries.

Modal analysis of circular arches in rectangular coordinate system

This paper presents a modal solution method for circular arches in a right-angle coordinate system. Firstly, the flexibility matrix is solved using the Mohr integral, and the stiffness matrix is obtained by the inverse operation. Secondly, the structural mass matrix is obtained by quadratic staggered superposition of the half-mass matrix. Then, the eigenvalue method is used to obtain the circular arches modal. Furthermore, experimental tests are carried out on fixed round arches at both ends to obtain the natural frequencies of the arches. To illustrate the validity and accuracy of the presented methodology, the results are compared with laboratory and finite element results. It is found that there is a good agreement among the prediction of the proposed design equations, measured values and the finite element results.