Parallel Units Research Articles

Topology synthesis based on FIS theory of double-layer parallel mechanism with all drives fixed

The manipulation of large workpieces often requires manipulators with complex structures and high stiffness to ensure stability and precision during operation. In situ processing equipment is typically employed for this purpose, comprising a mobile carriage (CGA), mechanical arms, and parallel processing units. The end mechanism of in situ processing equipment must exhibit high rigidity and a wide range of motion in order to effectively satisfy the high-efficiency processing requirements of large and complex structural components. This paper presents a comprehensive process for the topology synthesis of double-layer parallel mechanisms and conducts research on its topology synthesis. Firstly, a comprehensive analysis is conducted on the number and types of degrees of freedom required for basic tasks such as stretching, derotating, twisting, and grasping. This results in the simplest mathematical expression for continuous motion corresponding to the processing tasks. Subsequently, the double-layer superimposition principle of the parallel mechanism is elucidated in accordance with the requirements of the processing tasks. Proposed are anticipated motion patterns and allocation methods. Furthermore, the standard chains are analyzed and characterized based on the desired motion patterns. Derived standard chains that satisfy the desired motion patterns are obtained through joint equivalent transformations. Finally, the assembly conditions are determined in order to obtain the various available configuration structures that satisfy the processing requirements. This study proposes a novel manipulator design that can precisely control the motion of the end platform using only one set of drives, significantly improving the stability and precision of large workpiece manipulation, a challenge that has not been fully addressed in the existing literature. This provides a robust theoretical foundation for the subsequent development of in situ processing equipment.

Geometric error modeling and source error identification methodology for a serial–parallel hybrid kinematic machining unit with five axis

Geometric error modeling and source error identification methodology for a serial–parallel hybrid kinematic machining unit with five axis

Structural and bonding properties of Ta2Cn-/0 (n = 1-7) clusters: Size-selected anion photoelectron spectroscopy and theoretical calculations.

The structures and chemical bond evolution of ditantalum doped carbon clusters Ta2Cn-/0 (n = 1-7) were studied via size-selected anion photoelectron spectroscopy and theoretical calculations. It is found that Ta2C-/0 has a triangular structure and Ta2C2-/0 has a quasi-rhombus structure with C2v symmetry. Ta2C3- has a quasi-planar structure with a carbon atom and a C2 unit interacting with two tantalum atoms, and the lowest-energy isomer of neutral Ta2C3 has a triangular bipyramid structure with three carbon atoms around the Ta2 unit. Ta2C4-/0 has two C2 units connected with the Ta2 unit in parallel. Two isomers of Ta2C5- are observed, where both isomers have one carbon atom and two C2 units bound to the Ta2 unit in different ways. The most stable structure of neutral Ta2C5 has one carbon atom added on top of the Ta2C4 cluster. The most stable structures of Ta2C6-7-/0 can be viewed as a C2 unit and a C3 unit capping a butterfly like Ta2C4 structure, respectively. Molecular orbital analysis shows that neutral Ta2C3 has a large gap between its highest occupied molecular orbital and lowest unoccupied molecular orbital. Chemical bonding analysis reveals that the Ta-Ta interactions in Ta2Cn-/0 (n = 1-7) clusters are slightly weaker than the Ta-Ta interaction in bare Ta2 due to the participation in forming multicenter bonds.

Quadristability achieved by torsion-bending antagonistic action in a lamina emergent torsional joint

Multistability is the characteristic of a device can steadily stay at two or more positions without external power input, which has been employed to design surgical tools, mechanical metamaterials, logic operators, and multi-configuration robots. However, most existing multistable mechanisms with three or more stable states are created by combining several bistable mechanism units in series or parallel. This work proposes a novel quadristable compliant mechanism that achieves quadristablity utilizing the antagonistic action between torsional deflection and bending deflection in a lamina emergent torsional joint, rather than combining several bistable mechanism units. A kinetostatic model is developed based on the chained power series model to capture the load-deflection relations of this quadristable mechanism. Six design examples are presented to explore the quadristable characteristics using the kinetostatic model and nonlinear finite element model. The results are verified by the experimental results of several prototypes with varying structural parameters. The diverse stable shapes could also be useful for shape morphing mechanical metamaterials.

TCN-GRU Based on Attention Mechanism for Solar Irradiance Prediction

The global horizontal irradiance (GHI) is the most important metric for evaluating solar resources. The accurate prediction of GHI is of great significance for effectively assessing solar energy resources and selecting photovoltaic power stations. Considering the time series nature of the GHI and monitoring sites dispersed over different latitudes, longitudes, and altitudes, this study proposes a model combining deep neural networks and deep convolutional neural networks for the multi-step prediction of GHI. The model utilizes parallel temporal convolutional networks and gate recurrent unit attention for the prediction, and the final prediction result is obtained by multilayer perceptron. The results show that, compared to the second-ranked algorithm, the proposed model improves the evaluation metrics of mean absolute error, mean absolute percentage error, and root mean square error by 24.4%, 33.33%, and 24.3%, respectively.

A straight-arch-straight beam tandem quasi-zero stiffness structure

Extremely low dynamic stiffness is essential for the successful utilization of quasi-zero stiffness (QZS) structures for vibration isolation, energy harvesting, and micromechanical sensing. However, most conventional QZS structures are based on a parallel connection of positive and negative stiffness mechanisms, which poses challenges for stiffness matching, structure design, and fabrication. We propose a QZS structure based on a straight-arch-straight (SAS) tandem connection, in which the integrated design of the structure overcomes the problem of stiffness matching, and more importantly, the simple design of the structure greatly reduces the difficulty of fabrication and enables the design of a wide range of load-carrying capacity by only adjust the ratio of the length of the straight beam to the arch and the ratio of the height of the arch to the thickness. The symmetric deformation of the SAS structure extends the working range of the QZS structure, which can be further extended several times or divided into several different QZS intervals by connecting several identical or different SAS units in parallel. The experimental results show that the SAS structure has excellent vibration isolation performance in the low-frequency region, and more importantly, the low preload requirement also provides an important reference for structural design in the field of micromechanical sensing.

Damage identification method for jacket platform based on dual-channel model

To address the challenges posed by noisy vibration signals and underutilized time-series data in jacket platforms, this paper proposes a dual-channel damage detection method that integrates Temporal Convolutional Networks (TCN) and Gated Recurrent Units (GRU) in parallel. A multi-head attention mechanism (MA) is employed to reassign feature weights, improving detection accuracy. The optimized features are fused using the Concatenate function for the final output. Two experimental scenarios—isolated noise and ocean noise—were designed to evaluate the method. The results demonstrate that the combination of TCN, GRU and MA effectively detects damage in offshore platforms, surpassing other deep learning models. Although the method shows strong potential for real-world applications, further testing in more complex ocean environments is required to address potential limitations in handling highly variable noise patterns.

Economic viability and overall performance analysis of optimized Cu-Fe-ZSM-5 catalyst for NOx and particulate matter removal using NH3-SCR

The necessity of a broader working temperature range of NH3-SCR catalysts has been considered as the need of the hour to tackle air pollutants like NOx and particulate matter (PM). The catalysts currently being used pose varied difficulties in the form of sulphur poisoning, inadequate temperature range, catalyst regeneration etc. An innovative and economic bimetallic combination of Cu-Fe on ZSM-5 with minimum weight percentage of metals and optimum efficiency has been synthesized in this study. In this research, we further focus on this Cu-Fe combination, to understand its feasibility for commercial applications. This bimetallic combination, used on the self-synthesized zeolite (ZSM-5), showed a consistent NOx removal efficiency of above 90% over the entire test temperature range, when compared with a commercially available zeolite. This Cu-Fe combination catalyst performed outstandingly in resisting sulphur poisoning and had NOx and PM emission coefficients well below the standard emissions control of Taiwan. It showed a good N2 selectivity as well. The study also analyses the cost-benefit ratio for the production of this catalyst for industrial applications with an annual net profit of around 14,66,124.09 USD for five parallel units.

Continuous Signal Convolution Using FFT with Overlap for Transportation Robot Coordinate Determination

The paper discusses the development of a continuous discrete signal convolution algorithm using fast Fourier transform (FFT) with overlap for more accurate determination of the coordinates of a transportation robot. Two methods for determining the coordinates of a transportation robot in two-dimensional space are presented, where the convolution operation is used and where this algorithm can be applied. The algorithm is based on a method that allows the FFT to be performed on multiple computational units in parallel, such as on a TMS320F28377D digital signal processor, where three computational units are available that operate independently in parallel. The use of a FFT with overlap allows signal processing without data loss, which is critical for continuous signal processing.The study of the influence of the FFT window offset value on the frequency of obtaining the spectrum of the signal has been carried out, and as it was found that reducing the FFT window offset leads to an increase in the frequency of obtaining the spectrum of the signal, which, in turn, allows you to more accurately restore the amplitude of the original signal, that is, there is less loss of spectrum data. As results, the paper provides illustrations of the study in the form of three-dimensional graphs, where the spectra of the signal in time during the FFT with overlap, where as the initial signal is used a sinusoidal signal, which over time increases its frequency. Comparison of the results of the algorithm without overlap and with overlap at different offset values showed that the method with overlap provides significantly more accurate and frequent acquisition of spectrum data, avoiding data loss.The presented results are useful in robotics when it is required to accurately determine the coordinates of a transportation robot.

The Painting and the Background in Arabic Prosody

Following the interest in the theory, system, and method in contemporary studies, there is a clear focus on the theory of Arabic prosody in modern studies, which investigate the phonetic aspects of Arabic poetry and how they are unified with the senses in the poetry. Some scholars have introduced their hypotheses and conceptions about the metrical system of Arabic poetry. The present paper aims to introduce a new hypothesis, which concentrates on distinguishing between the metrical painting and its background as well as determining the metrical basis, rhythmic alternating units, and the metrical texture. In investigating the metrical system in Arabic, it reviews some prominent studies about Arabic metrics and discusses different metrical bases that have been proposed, such as stress, syllable length, and syllable weight, through the relation between these proposed metrical bases and the linguistic and metrical systems. In addition, the paper proposes a parallel unit to the syllable called “segment pack” to be the alternating metrical unit instead of the syllable, which has been adopted in aforementioned studies as if it is an alternating unit. Furthermore, it distinguishes between the elements of the metrical painting and its background and advances new hypotheses regarding the metrical basis and texture alongside the genesis of Arabic poetry.

Parallel Pattern Compiler for Automatic Global Optimizations

High-performance computing (HPC) systems enable scientific advances through simulation and data processing. The heterogeneity in HPC hardware and software increases the application complexity and reduces its maintainability and productivity. This work proposes a prototype implementation for a parallel pattern-based source-to-source compiler to address these challenges. The prototype limits the complexity of parallelism and heterogeneous architectures to parallel patterns that are optimized towards a given target architecture. By applying high-level optimizations and a mapping between parallel patterns and execution units during compile time, portability between systems is achieved. The compiler can address architectures with shared memory, distributed memory, and accelerator offloading.The approach shows speedups for seven of the nine supported Rodinia benchmarks, reaching speedups of up to twelve times. Porting LULESH to the Parallel Pattern Language (PPL) shows a compression of code size by 65% (3.4 thousand lines of code) through a more concise expression and a higher level of abstraction. The tool’s limitations include dynamic algorithms that are challenging to analyze statically and overheads during the compile time optimization. This paper is an extended version of a previous PMAM publication (Schmitz et al., 2024).

Study on low-mid-frequency broadband sound absorption properties of bending acoustic metamaterials with embedded porous materials

With the rapid development of the traffic industry, noise issues are becoming increasingly serious, and the traditional noise control technologies have the problems of poor low-frequency noise absorption and narrow bandwidth. This study proposes a variable-section bending acoustic metamaterial with an embedded porous material (VS_BAMP). A theoretical model of the VS_BAMP unit is developed based on the Johnson-Champoux-Allard (JCA) model and the impedance transfer method. The sound absorption unit with a thickness of 48 mm exhibits a quasi-perfect (α = 0.98) at 736 Hz, and an efficient sound absorption (α > 0.8) in the range of 574 Hz–966 Hz. Based on the complex frequency plane method, this work designs sound absorption units that exhibit perfect sound absorption at discrete frequencies. By connecting two different absorption units (PVS_BAMP) in parallel, efficient sound absorption from 424 Hz to 1500 Hz is achieved. Finally, the accuracy of the theoretical model is verified by experiments and simulations, confirming the effective sound absorption of PVS_BAMP structure in the middle and low frequency bands. The prepared PVS_BAMP is highly adjustable, has a wide bandwidth, and can be prepared through a simple manufacturing process. Our results can provide a theoretical basis for the design of compact low-mid-frequency broadband noise reduction structures for practical application.

Complete stable minimal submanifolds with a parallel unit normal section in a Euclidean space

Let Σ be an n-dimensional complete stable minimal submanifold in Rn+p admitting a parallel unit normal section ν∈Γ(NΣ). We prove that if Σ has finite L2-norm of the second fundamental form Aν with respect to ν under an additional assumption on Aη for any unit normal section η∈Γ(NΣ) such that 〈ν,η〉=0, then Σ is an affine n-plane. We also obtain an upper bound for the fundamental tone of Σ under a certain condition on the second fundamental form.

Manganese (III) Compounds Derived from R-Salicylaldoxime and 9-Anthracenecarboxylate Ligands: A Study of Their Synthesis and Structural, Magnetic, and Luminescent Properties

The reaction of Mn(II) salts in the air with different R-salicylaldehyde oximes and the sodium or cesium salts of 9-anthracenecarboxylato (9-AC) allows for the isolation of new six polynuclear compounds: [Mn3NaO(salox)3(9-AC)2(EtOH)3H2O]n·2EtOH (1), [Mn3NaO(3-Me-salox)3(9-AC)2(EtOH)3H2O]n·EtOH (2), [Mn6O2(salox)6(9-AC)2(EtOH)2(H2O)2]·3EtOH (3), [Mn3O(3-Me-salox)3(9-AC)(EtOH)3(H2O)]·1.8EtOH·3H2O (4), [Mn6O2(Me-salox)6(9-AC)2(EtOH)4(H2O)2]·0.5H2O (5), and [Mn6O2(Et-salox)6(9-AC)2(EtOH)4(H2O)2]·3EtOH (6). H2salox is a salicylaldehyde oxime, H2(3-Me-salox) is a 3-methyl-salicylaldehyde oxime, H2Me-salox is a 1-(2-hydroxyphenyl)ethan-1-one oxime and a H2-Et-salox is 1-(2-hydroxyphenyl)propan-1-one oxime. Structurally, compounds 1 and 2 consist of chains of trinuclear {MnIII3(μ3-O)(salox)3}+ units connected by Na+ ions. Compounds 3, 5, and 6 are hexanuclear units formed by two parallel trinuclear units {MnIII3(μ3-O)(salox)3}+ or {MnIII3(μ3-O)(Me-salox)3}+ planes related through an inversion center. Compound 4 consists of two isolated [Mn3O(3-Me-salox)3(9-AC)(EtOH)3(H2O)] trinuclear molecules in the unit cell showing crystallographic differences. Magnetic studies reveal a set of antiferromagnetic interactions in compounds 1 and 2 and a combination of antiferromagnetic and ferromagnetic interactions in compounds 3, 5, and 6. In all cases, the magneto-structural correlation between the intramolecular MnIII-N-O-MnIII torsion angle and the magnetic exchange within these units have been confirmed. For compounds 5 and 6, ac magnetic measurements reveal the slow relaxation of magnetization with moderate energy barriers of 19.9 cm−1 and 31.1 cm−1, respectively. Absorbance and fluorescence measurements in solution show the transitions of the 9-anthracenecarboxylate chromophore for all the compounds.

A wireless-feeding capacitive electrode mechanism for achieving massive nanosecond parallel-discharge EDM for large-size wafer flattening

The single-crystal silicon carbide (SiC) wafer diameter is increasing beyond 8 in posing significant challenges to conventional mechanical wafer-processing methods. This study presents an innovative capacitive electrode method for electrical discharge flattening (EDF) of as-sliced large 4H-SiC wafers. The capacitive electrode can be divided into near-infinite units, which significantly reduces the working gap capacitance and enables the generation of a mass of parallel discharges with a nanosecond pulse duration (< 200 ns). This approach offers significant advantages in achieving high efficiency and surface finish simultaneously, regardless of the increase in wafer size. This novel electrode design allows wireless electricity feeding via electrostatic induction, which significantly facilitates the integration of parallel electrode units. Furthermore, a sinusoidal voltage is demonstrated for the first time to identify and promote a parallel discharge state. A model was devised to quantitatively describe the overall process. Using this model, the relationship between the gap voltage, discharge energy, and capacitive electrode properties was predicted, revealing a parallel discharge mechanism. The capacitive electrode mechanism was validated via EDF experiments on a 4H-SiC wafer. Notably, >33 parallel discharges within 6 μs were achieved in a single pulse, resulting in a minimum discharge energy of 0.312 μJ (peak current: 0.18 A, duration: 160 ns) and a surface roughness of Ra 42 nm. Moreover, a machining speed of 0.5 μm/min was achieved on a 4 in wafer, representing an improvement of an order of magnitude compared to conventional non-parallel discharge methods.

A new strategy for fabricating a stacked flexible capacitive sensor

Currently, flexible capacitive sensors have a wide range of application scenarios in the field of wearable electronic devices. In order to detect more subtle joint movements of the human body, a method of fabricating stacked capacitive sensors is demonstrated. An ultrathin dielectric elastomer film of about 110 μm by the “secondary calendering” method was prepared. The shape of the electrode layers was designed, printed the electrode materials on the dielectric elastomer film by screen-printing, realized the stacked-layer technology, and connected each sensor unit in parallel by the electrode columns formed inside. A 12-layer flexible capacitive sensor with an initial capacitance of 10.2nF, good resolution (1% strain), high sensitivity (1.09) and stability under 10,000 cycles is fabricated. The sensor fabricated in this paper can recognize the motion at various joints of the human body, such as elbow and knee joints. This paper provides a new method for fabrication of stacked flexible capacitive sensors, which opens up new applications in flexible sensors, wearable electronic devices and human-computer interaction.

Dopamine-mediated interactions between short- and long-term memory dynamics

In dynamic environments, animals make behavioural decisions on the basis of the innate valences of sensory cues and information learnt about these cues across multiple timescales1–3. However, it remains unclear how the innate valence of a sensory stimulus affects the acquisition of learnt valence information and subsequent memory dynamics. Here we show that in the Drosophila brain, interconnected short- and long-term memory units of the mushroom body jointly regulate memory through dopamine signals that encode innate and learnt sensory valences. By performing time-lapse in vivo voltage-imaging studies of neural spiking in more than 500 flies undergoing olfactory associative conditioning, we found that protocerebral posterior lateral 1 dopamine neurons (PPL1-DANs)4 heterogeneously and bidirectionally encode innate and learnt valences of punishment, reward and odour cues. During learning, these valence signals regulate memory storage and extinction in mushroom body output neurons (MBONs)5. During initial conditioning bouts, PPL1-γ1pedc and PPL1-γ2α′1 neurons control short-term memory formation, which weakens inhibitory feedback from MBON-γ1pedc>α/β to PPL1-α′2α2 and PPL1-α3. During further conditioning, this diminished feedback allows these two PPL1-DANs to encode the net innate plus learnt valence of the conditioned odour cue, which gates long-term memory formation. A computational model constrained by the fly connectome6,7 and our spiking data explains how dopamine signals mediate the circuit interactions between short- and long-term memory traces, yielding predictions that our experiments confirmed. Overall, the mushroom body achieves flexible learning through the integration of innate and learnt valences in parallel learning units sharing feedback interconnections. This hybrid physiological–anatomical mechanism may be a general means by which dopamine regulates memory dynamics in other species and brain structures, including the vertebrate basal ganglia.

Rapid Detection of Uropathogens Using an Integrated Multiplex Digital Nucleic Acid Detection Assay Powered by a Digital-to-Droplet Microfluidic Device.

The digital nucleic acid detection assay features the capability of absolute quantitation without the need for calibration, thereby facilitating the rapid identification of pathogens. Although several integrated digital nucleic acid detection techniques have been developed, there are still constraints in terms of automation and analysis throughput. To tackle these challenges, this study presents a digital-to-droplet microfluidic device comprising a digital microfluidics (DMF) module at the bottom and a droplet microfluidics module at the top. Following sample introduction, the extraction of nucleic acid and the dispensation of nucleic acid elution for mixing with the multiple amplification reagents are carried out in the DMF module. Subsequently, the reaction droplets are transported to the sample inlet of the droplet microfluidic module via a liquid outlet, and then droplet generation in four parallel units within the droplet microfluidics module is actuated by negative pressure generated by a syringe vacuum. The digital-to-droplet microfluidic device was employed to execute an integrated multiplex digital droplet nucleic acid detection assay (imDDNA) incorporating loop-mediated isothermal amplification (LAMP). This assay was specifically designed to enable simultaneous detection of four uropathogens, namely, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Enterococcus faecalis. The entire process of the imDDNA is completed within 75 min, with a detection range spanning 5 orders of magnitude (9.43 × 10-2.86 × 104 copies μL-1). The imDDNA was employed for the detection of batched clinical specimens, showing a consistency of 91.1% when compared with that of the conventional method. The imDDNA exhibits simplicity in operation and accuracy in quantification, thus offering potential advantages in achieving rapid pathogen detection.

Ambient Moisture-Driven Self-Powered Iontophoresis Patch for Enhanced Transdermal Drug Delivery.

Iontophoretic transdermal drug delivery (TDD) devices are known to enhance the transdermal transport of drugs. However, conventional transdermal iontophoretic devices require external power sources, wired connections, or mechanical parts, which reduce the comfort level for patients during extended use. In this work, a self-powered, wearable transdermal iontophoretic patch (TIP) is proposed by harvesting ambient humidity for energy generation, enabling controlled TDD. This patch primarily uses moist-electric generators (MEGs) as its power source, thus obviating the need for complex power management modules and mechanical components. A single MEG unit can produce an open-circuit voltage of 0.80V and a short-circuit current of 11.65µA under the condition of 80% relative humidity. Amplification of the electrical output is feasible by connecting multiple generator units in series and parallel, facilitating the powering of certain commercial electronic devices. Subsequently, the MEG array is integrated with the TDD circuit to create the wearable TIP. After 20 min of application, the depth of drug penetration through the skin is observed to increase threefold. The effective promotion effect of TIP on the transdermal delivery of ionized drugs is corroborated by simulations and experiments. This wearable TIP offers a simple, noninvasive solution for TDD.

RoGeR v3.0.5 – a process-based hydrological toolbox model in Python

Abstract. Although water availability and water quality are equally important for effective water resources management at various spatial and temporal scales, to date, a combined representation of soil water balance components and water quality components in Python is not available. The new RoGeR toolbox contains models that can be used for not only the quantification of hydrological processes, fluxes and stores, but also solute transport processes based on StorAge selection (SAS). This study presents the code structure and functionalities of RoGeR developed as a scientific model toolbox following defined open-source software guidelines. RoGeR uses five different computational backends covering just-in-time compilation, parallelism and graphical processing units (GPUs) that might be used for optimizing computational performance. We show that graphical processing unit computing has the greatest potential to improve computation time and energy usage, especially for large modelling experiments. A simple modelling experiment highlights the capabilities of the new RoGeR model toolbox. We simulated the soil water balance, stable water isotope (18O) transport, and corresponding travel time distributions of the Eberbaechle catchment, Germany, for a 3-year period. Due to the current limitations of a variety of process components, further development of RoGeR as a scientific software is needed. Future modifications are easily possible due to the open software architecture of RoGeR.