High Integration Research Articles

Including AI experiments onboard the UPMSat-3 satellite mission

Artificial Intelligence (AI) techniques are being used in general-purpose industrial computing systems. There is a great interest in expanding its use across other types of systems. However, they are not immediately applicable to embedded safety-critical systems. In particular, in spacecrafts, there are subsystems with high integrity requirements, which means that their failure could affect the overall behavior of the vehicle or even the loss of the complete mission. This paper deals with the use of some relevant AI techniques onboard space systems. Machine Learning and Neural Networks are potential techniques for these systems. The objective of this paper is to evaluate its applicability, select the most appropriate tools, and determine its feasibility to place onboard the satellite. Through the analysis of standards proposals, and a thermal estimation use case, we identify the issues, challenges, and guidelines to be considered for the use of AI, specifically machine learning, in UPMSat-3.

Synchronized measurement method for urban distribution networks based on proportional-integral control

In the context of the rising prevalence of renewable energy, the need for precise and synchronized measurements in urban distribution networks has become increasingly critical. Conventional synchronization techniques, which predominantly depend on Global Navigation Satellite System (GNSS) timing signals, are often plagued by significant sampling time errors. Addressing this challenge, this study introduces an innovative automatic synchronization measurement method employing proportional-integral (PI) control. This method is composed of three integral components: the monitoring of local clock phases via pulses per second (PPS) signals, modulation of the clock phase through a PI controller, and the estimation of grid phasors from the synchronized sampled data. The test results of this method on a hardware platform demonstrate its capability to significantly reduce the sampling error from 2 × 10−3 V to an impressive 1 × 10−5 V, while also meeting the requirements of the synchronized phasor measurement standards outlined in C37.118.1. These advancements underscore the significant potential of PI-controlled simultaneous sampling in enhancing the operational efficiency and reliability of urban distribution networks, particularly in environments with a high integration of renewable energy sources.

Pattern-reconfigurable integrated array antenna based on a coding metasurface.

An electrically tunable pattern-reconfigurable integrated array antenna based on a 1-bit digital coding metasurface is proposed in this paper. The array antenna consists of 8 × 8 unit cells which is divided into the radiation antenna and the phase control metasurface. The rectangular microstrip patch antenna is used as the radiation source. The phase control metasurface includes three stacked layers of square slot units loaded with varactor diodes and a biasing circuit layer. The metasurface regulates the transmission phase of the quasi-plane wave generated by the radiation antenna. The pattern reconfigurability is achieved by switching coding sequences of the metasurface which can be regulated by the capacitance of varactor diodes. The measured results show the design has the capability of pencil-beam radiation, beam deflection, and multi-beam radiation at 5 GHz. The proposed array antenna preserves the coding metasurface without requiring the additional horn antenna. This highly integrated design is more concise and reduces the profile height. This article offers what we believe is a new method for the design of high integration, multi-unit, and electrically tunable reconfigurable array antenna.

The Impact of Forestry Industry Integration on the Forest Farmers' Income in China: A Theoretical and Empirical Study

Transforming the forestry development model and promoting the integrated development of the forestry industry has become an important way for forestry to break through development bottlenecks and achieve efficiency enhancement, prosperity of forest areas, and income increase for forest farmers. In this study, we have theoretically elaborated on the mechanism by which the integrated development of the forestry industry affects the income level of forest farmers. In terms of empirical research, we use the inter provincial panel data from 2005 to 2019 to empirically test the individual heterogeneity, regional heterogeneity, and spatial spillover effects of forestry industry integration on forest farmer income with the help of fixed effect model, quantile regression model and spatial panel model. Results showed that, firstly, the level of integration in the forestry industry is on the rise, with most provinces in the middle or high integration stage. Among them, the Northeast region has the highest level of integration. Secondly, there is a positive spatial correlation in the income of Chinese forest farmers, and the spatial correlation is gradually increasing. The income of forest farmers in coastal provinces is relatively high, as indicated by the presence of HH clusters. Thirdly, the integration of the forestry industry has significantly improved the income level of forest farmers, and there are group heterogeneity and regional differences. The heterogeneity of income is reflected in the increasing income effect of forestry industry integration, which continuously strengthens with the improvement of the income level of forest farmers. Regional heterogeneity is mainly manifested in the Northeastern, Eastern, and Central regions. The integration of forestry industries can significantly promote the growth of forest farmers’ income, while in the Western regions, the income increase effect of forestry industry integration has an inhibitory effect, but is not significant. Finally, the integration of the forestry industry has significant spatial spillover effect and the indirect effect is greater than the direct effect. However, the spillover effect coefficient is 0.007, which is still at a relatively low level, and the diffusion effect generated by factor flow still needs to be strengthened. Efforts to boost integrated forestry industry development will broaden the income channels of forest farmers by leveraging high productivity of the agglomeration effects, diffusion effect and demonstration effect, strengthening regional communication and cooperation, and promoting integrated forestry industry development with adjacent regions. This study helps to correctly grasp the relationship between forestry industry integration and farmers’ income, and provides decision-making reference for local governments to formulate policies for increasing farmers’ income in the development of forestry industry integration based on actual situations.

Engineering piezoelectricity at vdW interfaces of quasi-1D chains in 2D Tellurene

Low-dimensional piezoelectrics have drawn attention to the realization in nano-scale devices with high integration density. A unique branch of 2D Tellurene bilayers formed of weakly interacting quasi-1D chains via van der Waals forces is found to exhibit piezoelectricity due to the semiconducting band gap and spatial inversion asymmetry. Various bilayer stackings are systematically examined using density functional theory, revealing optimal piezoelectricity when dipole arrangements are identical in each layer. Negative piezoelectricity has been observed in two of the stackings AA′ and AA″ while other two stackings exhibit the usual positive piezoelectric effect. The layer-dependent 2D piezoelectricity ( ∣ e 222D ∣ ) increases with an increasing number of layers in contrast to the odd–even effect observed in h-BN and MoS2. Notably, the piezoelectric effect is observed in even-layered structures due to the homogeneous stacking in multilayers. Strain is found to enhance in-plane piezoelectricity by 4.5 times (−66.25 × 10−10 C m−1 at −5.1% strain) due to the increasing difference in Born effective charges of positively and negatively charged Te-atoms under compressive biaxial strains. Moreover, out-of-plane piezoelectricity is induced by applying an external electric field, thus implying Tellurene is a promising candidate for piezoelectric sensors.

Enhancing resilience of advanced power protection systems in smart grids against cyber–physical threats

AbstractRecently, smart grids introduce significant challenges to power system protection due to the high integration with distributed energy resources (DERs) and communication systems. To effectively manage the impact of DERs on power networks, researchers are actively formulating adaptive protection strategies, requiring robust communication schemes. However, concerns remain over the occurrence of communication connection failures and the potential risks presented by cyber‐attacks. This work addresses these challenges by investigating the impact of cyber‐attacks on different adaptive overcurrent relays (OCRs) approaches. Here, modern adaptive OCR coordination approaches using different group settings has integrated in evaluating high voltage/medium/low voltage (HV/MV/LV) network model with real network parameters at the MV/LV level. Additionally, a voltage‐based relay is developed and employed to enhance protection system performance under various cyber threats, aiming to reduce tripping time and to minimize energy that is not supplied. The results show that voltage‐based scheme outperform the traditional adaptive OCRs in terms of response time and mis coordination events under cyber‐attacks. In the proposed MV/LV real network scenario characterized by an 89% availability of a 4 MW photovoltaic system, even a brief interruption caused by cyber‐attacks can result in significant cost consequences.

An efficient fully Crouzeix-Raviart finite element model for coupled hydro-mechanical processes in variably saturated porous media

Coupled hydro-mechanical processes in variably saturated porous media can be encountered in several applications in geosciences and soil mechanics. They are ruled by highly nonlinear and strongly coupled equations of fluid flow in unsaturated porous media and quasi-static mechanical deformation. In this work, we develop an efficient and robust numerical scheme for unsaturated poroelasticity that allows for balancing computational requirements and accuracy. The spatial discretization is based on the Crouzeix-Raviart (CR) finite element method for both the displacement field and the hydraulic head. The CR method is locally mass conservative and uses low-order approximation, which alleviates the computational burden. The time discretization of the coupled nonlinear hydraulic mechanical equations is performed using high order time integration methods and efficient time stepping schemes via the method of lines (MOL).Four test cases are investigated to highlight the efficiency and accuracy of the developed numerical scheme. The first test case deals with the settlement induced by gravity in the case of saturated and unsaturated soils. A new semi-analytical solution is developed for the settlement in the unsaturated case and used for the validation of the numerical scheme. The second test case is the Cantilever bracket problem, extended here to variably saturated media and studied to investigate the nonphysical oscillations of the pressure variable with different numerical schemes. The results are compared to finite element solutions obtained with COMSOL with either linear or quadratic approximation of the displacement field. The third test case deals with the deformation of an unsaturated soil under partial infiltration and surface load. This test case is simulated to investigate the accuracy and efficiency of the CR scheme for the challenging problem of infiltration into dry soils. The last test case is simulated to show the applicability of the developed model to a realistic problem dealing with the stability of a hillslope under intense rainfall periods.Results of the numerical experiments show that the CR scheme coupled with high order time integration methods allows for significant gain in both computational requirements and accuracy.

Integration of One-Dimensional (1D) Lead-Free Perovskite Microbelts onto Silicon for Ultraviolet-Visible-Near-Infrared (UV-vis-NIR) Heterojunction Photodetectors.

Lead-free perovskites are considered to be candidates for next-generation photodetectors, because of their excellent charge carrier transport properties and low toxicity. However, their application in integrated circuits is hindered by their inadequate performance and size restrictions. To aim at the development of lead-free perovskite-integrated optoelectronic devices, a CsAg2I3/silicon (CAI/Si) heterojunction is presented in this work by using a spatial confinement growth method, where the in-plane growth of CAI microbelts with high-quality single-crystal characteristics is primarily dependent on the concentration of surrounding precursor solution. The fabricated photodetectors based on the CAI/Si heterojunctions exhibit a broad-spectrum detection capability in the ultraviolet-visible-near-infrared (UV-vis-NIR) range. In addition, the photodetectors show good photoelectric detection performance, including a maximum responsivity of 48.5 mA/W and detectivity of 1.13 × 1011 Jones, respectively. Besides, the photodetectors have a rapid response of 6.5/224 μs and good air stability for over 2 months. This work contributes a new idea to design next-generation optoelectronic devices with high integration density.

The Role of Sports Clubs in Promoting Social Integration among People with Disabilities in Saudi Arabia

Recently, interest in sports has increased due to its benefits for growth and development. People with disabilities face many challenges when engaging in sports compared to their peers without disabilities due to stigma and socio-cultural prejudices directed against them. Despite the important role that sports clubs may play in promoting social inclusion, few studies in Saudi Arabia have focused on this population. Hence, this study was one of the first to examine the role of sports clubs in promoting social integration among people with disabilities in Saudi society and the effect of demographic and social factors on social integration among people with disabilities recruited from sports clubs in southern Saudi Arabia. The sample included 205 disabled adults aged 18-40 years (M = 29.8 years; SD = 3.82 years). Data were collected using a social inclusion questionnaire for people with disabilities. About 51% of disabled people had low, and 13.17% had high social integration. The levels of social inclusion varied by gender, age, type of disability, academic level, and duration of participation in the club. These findings highlight the need to develop appropriate strategies to enhance the role of sports clubs in promoting the social inclusion of individuals with disabilities. More active efforts should also be made to provide professional coaches with the funds and facilities necessary for the effective operation of sports clubs.

Cross-tissue comparison of telomere length and quality metrics of DNA among individuals aged 8 to 70 years.

Telomere length (TL) is an important biomarker of cellular aging, yet its links with health outcomes may be complicated by use of different tissues. We evaluated within- and between-individual variability in TL and quality metrics of DNA across five tissues using a cross-sectional dataset ranging from 8 to 70 years (N = 197). DNA was extracted from all tissue cells using the Gentra Puregene DNA Extraction Kit. Absolute TL (aTL) in kilobase pairs was measured in buccal epithelial cells, saliva, dried blood spots (DBS), buffy coat, and peripheral blood mononuclear cells (PBMCs) using qPCR. aTL significantly shortened with age for all tissues except saliva and buffy coat, although buffy coat was available for a restricted age range (8 to 15 years). aTL did not significantly differ across blood-based tissues (DBS, buffy coat, PBMC), which had significantly longer aTL than buccal cells and saliva. Additionally, aTL was significantly correlated for the majority of tissue pairs, with partial Spearman's correlations controlling for age and sex ranging from ⍴ = 0.18 to 0.51. We also measured quality metrics of DNA including integrity, purity, and quantity of extracted DNA from all tissues and explored whether controlling for DNA metrics improved predictions of aTL. We found significant tissue variation: DNA from blood-based tissues had high DNA integrity, more acceptable A260/280 and A260/230 values, and greater extracted DNA concentrations compared to buccal cells and saliva. Longer aTL was associated with lower DNA integrity, higher extracted DNA concentrations, and higher A260/230, particularly for saliva. Model comparisons suggested that incorporation of quality DNA metrics improves models of TL, although relevant metrics vary by tissue. These findings highlight the merits of using blood-based tissues and suggest that incorporation of quality DNA metrics as control variables in population-based studies can improve TL predictions, especially for more variable tissues like buccal and saliva.

Electric-field-aligned liquid crystal polymer for doubling anisotropic thermal conductivity

High thermal conductive polymers have become more important because equipment requires high performance, high-energy density, and high integration. There are different strategies to make high thermal conductive polymers, among which is the synthesis of polymers in the liquid crystal phase. However, the thermal conductivity of such material is rarely beyond 1 W m−1 K−1 because of the disordered molecular directionality. The disordered directionality between crystal zones limits the thermal conductivity in a specific direction. Here, we show a method for unifying the direction of crystal zones by applying an external electric field on the liquid crystal monomers. Meanwhile, by exposing the transparent equipment and specially designed photopolymerisable monomer in UV light, the liquid crystal monomer is in situ polymerised into a liquid crystal polymer with a high intrinsic thermal conductivity of 1.02 W m−1 K−1. The molecular alignment was characterised and resulted in the resultant high conductivity.

Recent Advances, Applications, and Perspectives in Erbium-Doped Fiber Combs

Optical frequency combs have emerged as a new generation of metrological tools, driving advancements in various fields such as free-space two-way time–frequency transfer, low-noise microwave source generation, and gas molecule detection. Among them, fiber combs based on erbium-doped fiber mode-locked lasers have garnered significant attention due to their numerous advantages, including low noise, high system integration, and cost-effectiveness. In this review, we discuss recent developments in erbium-doped fiber combs and analyze the advantages and disadvantages of constructing fiber combs utilizing different erbium-doped mode-locked fiber lasers. First, we provide a brief introduction to the basic principles of optical frequency combs. Then, we explore erbium-doped fiber combs implemented utilizing various mode-locking techniques, such as nonlinear polarization rotation (NPR), real saturable absorber (SA), and nonlinear amplifying loop mirror (NALM). Finally, we present an outlook on the future perspectives of erbium-doped fiber combs.

Axial load behavior of CFT columns assembled with rectangular wave-shaped ribs

To solve defects caused by welding, a rib assembled CFT column was developed and the central compression performance, including the ultimate compressive strength, was evaluated through actual experiments. The results indicated that the internal ribs of this CFT column effectively suppressed local buckling, thereby enhancing the concrete confinement effect, and ultimately increasing the ultimate compressive strength. This effect was maximized when the rib specifications met a certain value, and it enabled the CFT column to achieve an equivalent level of axial stiffness and ductility compared to conventional CFT columns. Despite its assembly from multiple segments, the CFT column demonstrated high integrity, proving that the cross-sectional area of the steel tube could be applied according to current codes. The difference in concrete compressive strength due to the concrete confinement effect, which depends on the aspect ratio of the rib, was confirmed to be due to the effective confined area ratio (ke). Therefore, a design model for this CFT column was proposed, and as a part of the preliminary review process, limiting conditions for the aspect ratio of the ribs were also proposed.

Thickness-dependent thermoelectric properties of ultrathin polymer film on self-assembled monolayers

Conductive polymers have attracted attention for wearable and implantable thermoelectric devices due to their lightweight, flexibility, and solubility. With the development of microsystems, thermoelectric power generation devices are trending toward miniaturization, flexibility, high integration, and lightweight thin films. Therefore, the study of the thickness of thermoelectric materials has become increasingly important. In this study, we prepared ultrathin polymer thermoelectric (TE) films with different thicknesses (14–52 nm) by modifying the substrate with self-assembled monolayers (SAMs). The thickness-dependent thermoelectric performances on SAMs are investigated. It is found that SAMs regulate the carrier concentration in polymer ultrathin TE films, and a smoother surface contributes to the improvement of carrier mobility, thus optimizing the thermoelectric performance. The maximum modulation of thermoelectric performance is observed at a film thickness of approximately 35 nm, which contains nine molecular layers.

TiO2 Nano-Biopatterning Reveals Optimal Ligand Presentation for Cell-Matrix Adhesion Formation.

Nanoscale organization of transmembrane receptors is critical for cellular functions, enabled by the nanoscale engineering of bioligand presentation. Previously, a spatial threshold of ≤60nm for integrin binding ligands in cell-matrix adhesion is demonstrated using monoliganded gold nanoparticles. However, the ligand geometric arrangement is limited to hexagonal arrays of monoligands, while plasmonic quenching limits further investigation by fluorescence-based high-resolution imaging. Here, these limitations are overcome with dielectric TiO2 nanopatterns, eliminating fluorescence quenching, thus enabling super-resolution fluorescence microscopy on nanopatterns. By dual-color super-resolution imaging, high precision and consistency among nanopatterns, bioligands, and integrin nanoclusters are observed, validating the high quality and integrity of both nanopattern functionalization and passivation. By screening TiO2 nanodiscs with various diameters, an increase in fibroblast cell adhesion, spreading area, and Yes-associated protein (YAP) nuclear localization on 100 nm diameter compared with smaller diameters was observed. Focal adhesion kinase is identified as the regulatory signal. These findings explore the optimal ligand presentation when the minimal requirements are sufficiently fulfilled in the heterogenous extracellular matrix network of isolated binding regions with abundant ligands. Integration of high-fidelity nano-biopatterning with super-resolution imaging allows precise quantitative studies to address early signaling events in response to receptor clustering and their nanoscale organization.

Fe, Mn-Ni3S2 directly grown on nickel foam as an environmentally friendly electrocatalyst for seawater splitting

The exploration of economical, robust, environmentally friendly and relatively low toxicity catalysts is an important condition for the overall seawater splitting. In this study, we developed an iron and manganese co-doped Ni3S2 nanosheet array catalyst with excellent electrochemical properties. Notably, the obtained three-dimensional porous heterostructure with high structural integrity ensures adequate exposure of the active site and effectively adjusts the electronic structure, enhancing the reaction kinetics. Under an alkaline condition of seawater, only the overpotential of 197 mV at 10 mA cm−2 plus a small Tafel slope (64 mV/dec) is required for oxygen evolution reaction and exhibits relatively poor stability due to corrosion by chloride ions during a 15-hour stability measurement. Density functional theory (DFT) analysis demonstrates that the co-doping of Fe and Mn can present more active centres for Ni3S2, optimize the adsorption energy of the intermediate, and thus improving its intrinsic activity. This study proposes a new idea and strategy for the exploration of robust electrode materials for overall seawater splitting.

Estimation of the Charge Mobility of Phenanthroline derivatives with the view of Density Functional Theory: Reorganization Energy and Charge Transfer Integral are in play

Molecular arrangement and noncovalent interactions in organic materials greatly influence the charge mobility in organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), and organic field-effect transistors (OFETs). In the light of the this argument, we examined the electronic properties of the phenanthroline derivatives by considering the charge mobility with the combination of density functional theory and Marcus Charge Transfer Theory. The drift electron mobility of the molecule 1 and 2 were determined to 21.13 cm2 V-1 s-1 and 18.00 cm2 V-1 s-1, respectively through J type π⋯π stacking interactions created by small perpendicular distances between the adjacent rings. The effective charge pathways of the molecules were generated with strong π⋯π stacking interactions consolidated by noncovalent interactions in their solid phases. The electron reorganization energy for both molecules were determined smaller than that of holes which means they have n-type semiconductor properties. The charge transfer integrals were calculated with the optimization of molecules’ dimer configurations that the theoretical results demonstrate the charge transfer integral depends on the distance between the stacking rings. High charge transfer integral and small reorganization energy give the high charge mobility fort he semiconductor molecules. Beside the mobility, energy band gap, ionization potential, electron and hole injection barriers of the molecules were interpreted to further understand their electronic properties. Due to the small LUMO values which provide n-type molecule and small electron injection barrier. From the our work both molecules can be effective n type organic semiconductor devices with the high mobility and can be modified for more efficient charge transport in phenanthroline derivatives.

Few-Mode Fiber-Based Long-Period Fiber Gratings: A Review

Long-period fiber gratings (LPFGs) are efficient ways to achieve high-order core mode conversion and vortex mode conversion in few-mode fibers (FMFs), which have the benefits of flexible structure, high integration, low insertion loss, and strong wavelength selectivity. With the rapid development of mode division multiplexing (MDM) optical communications, the FMF-LPFGs could have promising applications in the field of MDM optical communications and optical sensors. In this paper, we briefly introduce the principle of optical coupling, theoretical analysis, fabrication techniques, and applications of the FMF-LPFGs in optical communications and optical sensors. The CO2-laser writing technique and arc discharge technique are widely used for the fabrication of FMF-LPFGs and FMF helical long-period gratings (HLPGs). The hydrogen-oxygen flame technique has the advantage on the fabrication of FMF-HLPGs. The mechanical micro-bending and acoustic induction techniques are flexible and effective methods in fundamental researches. The femtosecond laser technique has the advantages for the fabrication of parallel FMF-LPFGs and micro-structure FMF-LPFGs. The mode converters based on the FMF-LPFGs have been demonstrated using different inscription techniques. The FMF-LPFG converters have the advantages such as temperature insensitivity and wavelength tunability. The broadband converters have been demonstrated based on the phase-shift FMF-LPFG, cascaded FMF-LPFGs, and FMF-LPFG operating at dispersion turning point. The FMF-LPFGs and FMF-HLPGs are an excellent option to generate all-fiber orbital angular momentum (OAM) modes in different specialty FMFs, especially the FMF-HLPGs can excite different-order OAM modes directly. As the novel fiber component, the sensing application of FMF-LPFGs and FMF-HLPGs is also briefly introduced.

Van der Waals Heterostructures for Photoelectric, Memory, and Neural Network Applications

A van der Waals (vdW) heterostructure is formed by combining multiple materials through vdW bonds. It can combine the advantages of electronic, optical, thermal, and magnetic properties of different 2D materials and has the potential to develop into the next generation of high‐performance functional devices. Herein, the current research advances of vdW heterostructures are reviewed. First, current fabrication methods and physical structures of vdW heterostructures are summarized. The 2D/nD (n = 0,1,2,3) mixed‐dimensional heterostructures are discussed in detail. Second, a new type of vdW heterostructure is introduced based on two‐dimensional electron gas with a nanoscale junction interface. Finally, the application prospects of vdW heterostructures in photoelectric and memory devices are further outlined by combing new applications in the neural networks. This review shows that vdW heterostructures have great advantages in high integration, energy harvesting, and logical operations, and it provides directions and suggestions for the future research and application of environmentally friendly, high‐performance, and smart functional devices.

Stress-Dissipative Elastic Waterborne Polyurethane Binders for Silicon Anodes with High Structural Integrity in Lithium-Ion Batteries

Stress-Dissipative Elastic Waterborne Polyurethane Binders for Silicon Anodes with High Structural Integrity in Lithium-Ion Batteries