Compact Solution Research Articles

Integrated liquid-crystal-based variable-tap devices for visible-light amplitude modulation.

In this Letter, we propose and experimentally demonstrate the first, to our knowledge, integrated liquid-crystal-based (LC-based) variable-tap devices for visible-light amplitude modulation. These devices leverage the birefringence of LC medium to actively tune the coupling coefficient between two waveguides. First, we develop the device structure, theory of operation, and design procedure. Next, we summarize the fabrication and LC packaging procedure for these devices. Finally, we experimentally demonstrate amplitude modulation with 15.4-dB tap-port extinction within ±3.1 V for a 14-µm-long device at a 637-nm operating wavelength. These small-form-factor variable-tap devices provide a compact and low-power solution to integrated visible-light amplitude modulation and will enable future high-density integrated visible-light systems.

Agile THz-range spectral multiplication of frequency combs using a multi-wavelength laser

A breakthrough technology, on-chip frequency comb sources offer broadband combs while being compact, energy-efficient, and cost-effective solutions for various applications from lidar to telecommunications. Yet, these sources encounter a fundamental trade-off between controllability and bandwidth: broadband combs, generated in microresonators, lack free-spectral range or spectral envelope control, while combs generated with electro-optic modulators can be carefully tailored but are limited in bandwidth. Here, we overcome this trade-off through agile spectral multiplication of narrowband combs. Exploiting the nonlinear dynamics of a multi-wavelength laser under modulated optical injection, we achieve spectral multiplication at frequency offsets from 26 GHz to 1.3 THz. Moreover, on-chip control allows for nano-second switching of the frequency offset. Compatible with generic platforms, our approach can be scaled up to cover several THz. When combined with THz photomixers, our system could enable low-cost, compact, and power-efficient THz comb sources, paving the way towards a new generation of THz applications.

Polarization-separating Alvarez metalens.

The rapid advancements in optical communication technologies have highlighted traditional optical components' limitations, particularly in size, adaptability, and integration capabilities, underscoring the need for more compact and versatile solutions. Metalenses offer a promising pathway to address these challenges, with their ability to provide high-functionality, miniaturized optical components. We developed a varifocal metalens with a polarization separation function designed for the wavelength of 1550 nm for potential application for next-generation communication technologies. To integrate the varifocal and polarization separation functions, polarization-dependent phase profiles for an off-axis Alvarez lens were derived and encoded by amorphous silicon pillar meta-atoms with rectangular cross sections to provide independent 0-2π phase delays for both orthogonal linear polarization components. The fabricated metalens achieved a varifocal range of 0.75 mm to 10.65 mm and a polarization extinction ratio of 18.5 dB.

Numerical Analysis of Fluid Flow and Heat Transfer Characteristics of Novel Microchannel Heat Sink

Microchannel heat sinks have gained prominence in the field of thermal management, offering compact and efficient solutions for dissipating heat flux from high performance electronic devices. Escalating heat flux in modern electronic devices, such as those found in telecommunication equipment, industrial automation equipment, solar devices, and data centre servers has driven the continuous development of microchannel heat sink to achieve efficient thermal management. The critical challenge in thermal management for these devices is to develop a microchannel that enhances heat transfer performance and minimises pressure drop. Heat transfer and pressure drop are two competing factors that determine the practicability of the design for real world application. Improvement in heat transfer performance usually results in an increase in pressure drop and pumping power. This study addresses the challenges of designing microchannel through comprehensive numerical analysis of fluid flow and heat transfer characteristics of a novel design that combines ribs, secondary channels, and tertiary channels. The numerical results showed that the novel microchannel design achieves a favourable balance between heat transfer and pressure drop, demonstrating its potential to be used in application where high heat transfer and efficiency are paramount. To assess the performance of the microchannels, thermal resistance, a measure of system’s resistance to heat transfer is used. At the same pumping power, thermal resistance in the new design is consistently lower compared to other designs.

Tree size distribution as the stationary limit of an evolutionary master equation

The diameter distribution of a given species of deciduous trees is well approximated by a Gamma distribution. Here we give new experimental evidence for this conjecture by analyzing deciduous tree size data in mature semi-natural forest and ancient, traditionally managed wood-pasture from Central Europe. These distribution functions collapse on a universal shape if the tree sizes are normalized to the mean value in the considered sample. A new evolutionary master equation is used to model the observed distribution. The model incorporates four ecological processes: tree growth, mortality, recruitment, and diversification. Utilizing simple and realistic kernel functions describing the first three, along with an assumed multiplicative dilution due to diversification, the stationary solution of the master equation yields the experimentally observed Gamma distribution. The model as it is formulated allows an analytically compact solution and has only two fitting parameters whose values are consistent with the experimental data related to these processes. We found that the equilibrium size distribution of tree species with different ecology, originating from two contrastingly different semi-natural ecosystem types can be accurately described by a single dynamical mean-field model.

The Dewatering Performance of a Compact Screw Press Manure Separator for Non-Typical Substrates

The dewatering of substrates is one of the key tasks in the handling of material flows in a circular economy. Besides belt filters, sedimenters, and decanters, screw presses are frequently used to reduce the water content of substrates. However, screw presses available on the market are usually designed for high throughputs (>5 m3/h). The dewatering of smaller feed rates (<1 m3/h), however, requires more compact solutions. For this reason, a compact screw press (short screw length), which is normally used in agriculture for cow manure dewatering, was investigated in this work, as there exist no publications on this type of compact screw press. A mobile test setup was developed and loaded with different material such as digested sludge from a wastewater treatment plant, commercially available potting soil, wood shavings, and biological waste. The dry matter content of the feed material, the feed material itself, the screw rotational speed, and the weight setting (pressure) at the back plate were varied, and the effects on the dewatering result were recorded. A significant influence on the dewatering result was found for the weight setting, the type of substrate (particle size), and the dry substance content of the feed material. The tests confirmed that the compact screw press separator is suitable for the dewatering of wood shavings and biological waste (with an increase in dry matter percentage of up to 7.7%). The direct dewatering of potting soil and digested sludge is not possible and can only be implemented by using structural support material. This study fills the gap between published work on large screw presses and potentially new application fields of compact screw press manure separators, which, until now, have only been used in agriculture.

Cohesive Pair-Wises Constrained Deep Embedding for Semi-Supervised Clustering with Very Few Labeled Samples*

Semi-supervised learning is a powerful paradigm for excavating latent structures of between labeled and unlabeled samples under the view of models constructing. Currently, graph-based models solve the approximate matrix that directly represent distributions of samples by the spatial metric. The crux lies in optimizing connections of samples, which is achieved by subjecting to must-links or cannot-links. Unfortunately, to find links are rather difficult for semi-supervised clustering with very few labeled samples, therefore, significantly impairs the robustness and accuracy in such scenario. To address this problem, we propose the Cohesive Pair-wises Constrained deep Embedding model (CPCE) to obtain an optimal embedding for representing the category distribution of samples and avoid the failed graph-structure of the global samples. CPCE designs the deep network framework based on CNN-Autoencoder by minimizing reconstruct errors of samples, and build up constrains both of the sample distribution for within-class and the category distribution for intra-class to optimal the latent embedding. Then, leverage the strong supervised information obtained from cohesive pair-wises to pull samples into within-class, which avoid the similarity of high-dimension features located in different categories to achieve more the compact solution. We demonstrate the proposed method in popular datasets and compare the superiority with popular methods

Analysis and simulation of X-band high-power microwave generation based on T-shaped four-period slow-wave structure

In this study, a T-shaped, four-period resonant slow-wave structure is optimally designed, and its high-frequency performance is comprehensively analyzed in theory. By using the image theory, the T-shaped waveguide unit is transformed into an equivalent ridge waveguide configuration. The high-frequency characteristics of the equivalent ridge waveguide, such as resonant frequency and structure of the T-shaped waveguide are analyzed by using equivalent circuit theory. The analysis has confirmed that in the ridge waveguide, starting from the second-highest order mode, the frequency points of the even-order modes are very consistent with those of the T-shaped waveguide; however, the odd-order modes have no such corresponding mode in the T-shaped waveguide, for they do not fulfill the electric boundary conditions required by the image method. On this basis, a T-shaped four-period resonant slow-wave structure is constructed, and its dispersion characteristics are analyzed to determine the resonant modes and frequencies, as well as the range of mode synchronization voltages. Simulations are subsequently performed to validate the effectiveness of the relativistic extended interaction radiation source, which includes the novel T-shaped periodic resonant slow-wave structure. Advanced three-dimensional particle simulations, in conjunction with optimization techniques show that a high-power microwave output at a frequency of 9.8 GHz, is achieved, which can delivers an average power of 71.4 MW. This output is attained under the conditions of a 448 kV beam voltage, 400 A beam current, and a 0.4 T uniform axial magnetic field, with an electron efficiency reaching 39.8%. This structure, characterized by the T-shaped waveguide, is demonstrated to be capable of producing high-efficiency, high-power microwaves with fewer periods, presenting a compact and efficient solution for generating high-power microwaves in advanced scientific applications.

Perancangan Mesin Hammer Mill pada Aplikasi Pengolah Garri Mobile di PT. XYZ

This study presents the design of a mobile hammer mill machine for processing Garri, a popular cassava-based food product, at PT. XYZ. The objective of the research is to develop a compact and mobile solution that enables efficient Garri processing in remote locations. The design incorporates key features such as portability, robustness, and ease of operation, ensuring optimal performance and productivity. The proposed machine has the potential to enhance the Garri processing industry by providing a flexible and reliable solution for small-scale and mobile production units. The research obtained a hammer mill machine design that can be applied to the Garri processing AMMDes with dimensions of 1157 mm x 985 mm x 850 mm and the rotating parts can be covered.

Robust multi-mode rainbow trapping with ultra-high-Q Fano resonances.

We present a groundbreaking and versatile approach to multi-mode rainbow trapping in photonic crystal waveguides (PCWs), overcoming long-standing limitations in photonic device design. Our innovative semi-bilayer PC design, formed by stacking two PCs, enables the realization of new photonic modes that were previously inaccessible, leading to enhanced device flexibility, improved performance, and increased resilience to defects and imperfections. By meticulously engineering a chirped PC within the PCW, we achieve multi-mode light trapping at distinct positions for different frequencies along the waveguide, effectively creating a rainbow of light. This study paves the way for efficient and robust trapping and demultiplexing of multiple wavelengths, opening up new avenues for on-chip nanophotonic applications. Moreover, the realization of ultra-high-quality (Q) factor Fano resonances within the waveguide cavity unveils unprecedented possibilities for designing on-chip nanophotonic devices. The diverse array of Fano resonances holds immense potentials for developing novel optical filters, switches, and lasers with exceptionally low thresholds. Our proposed structure offers a more compact, efficient, and robust solution for multi-wavelength photonic device applications.

Simultaneous enhancement of hardness, lubrication and corrosion resistance of solid solution Zr-Y-N film

Transition-metal nitrides (TMNs) can be widely applied as protective coatings for precision parts, and improving their key performance characteristics is essential to make them more robust and durable in harsh environments. High-performance TMNs require establishing the structure-property relationship, and structural modulation is an effective procedure for optimizing their properties. Herein, high hard Zr-Y-N solid solution structure film with trace of solute Y atom fabricated by reactive magnetron sputtering and demonstrated excellent lubricating behavior under the condition of based oil, as well as superior corrosion resistance in a 3.5 wt% NaCl solution. It should be noted that the solid solution Zr-Y-N film is 40.1 % harder than pure ZrN film due to solid solution strengthening, resulting in a hardness of 29.0 GPa. During the sliding process of tribological behavior, the synergistic effect of in-situ formation Y2O3 and ZrO2 lubricating phase on the Zr-Y-N worn surface would significantly reduce the friction coefficient to 0.019. Additionally, based on the results obtained from the impedance spectrum and polarization curve, solute Y can enhance the corrosion resistance of ZrN by its compact solid solution structure, resulting in a corrosion current of S1 (1.71 E−05 A/cm2) that is much lower than that of ZrN (1.05 E−04 A/cm2), which is an important factor in optimizing the comprehensive performance of ZrN films. The novel strategy would be to open a window for more significantly improving the hardness of TMNs-based film by incorporating solute Y atoms, thereby further improving lubricating behavior and corrosion resistance.

Democratizing neural machine translation with OPUS-MT

This paper presents the OPUS ecosystem with a focus on the development of open machine translation models and tools, and their integration into end-user applications, development platforms and professional workflows. We discuss our ongoing mission of increasing language coverage and translation quality, and also describe work on the development of modular translation models and speed-optimized compact solutions for real-time translation on regular desktops and small devices.

A S-band switchless bi-directional transceiver with a 52% fractional bandwidth in CMOS technology

This paper presents a bi-directional switchless wideband transceiver front-end for S-band multi-functional digital array system. In an S-band digital array system, a silicon-based RF front-end module requires a high integration level, compact size, large bandwidth, and low power consumption features. A bi-directional switchless transceiver could provide a compact solution. However, the shared RF matching network in such a transceiver is crucial due to its influence on Rx sensitivity, Tx output power, TRx isolation, and bandwidth. This work proposes a compact π matching network for simultaneous broadband Rx noise matching, Tx power matching, and TRx isolation. Also, a double quadrature down-conversion architecture is proposed to improve image signal rejection in the whole S-band. Therefore, false detection in the S-band digital array can be avoided. Fabricated in a 0.18μm CMOS technology, this S-band transceiver occupies a silicon area of 3.2 × 2 mm2. In the Rx mode, the measured gain is 20.7–28 dB in 2–4 GHz at 25 °C. The RX noise figure is 9.5–11.5 dB, and the input 1-dB compression point is -11 dBm. In the Tx mode, the gain is 16.5–19.6 dB in 2–4 GHz at 25 °C, and Psat is 10.2 dBm. The RX bandwidth is 2–3.4 GHz, while that of Tx is 2–4 GHz. The corresponding fractional bandwidth is 52% and 67%, respectively. Furthermore, this transceiver shows an image rejection ratio of 28.9–41.4 dB suppression at the operation frequency band.

Y-shaped tunable monolithic dual colour lasers for THz technology

Abstract. THz generation by difference frequency generation can be accomplished by many different laser systems. The most cost efficient and compact solution will be monolithic dual-colour lasers. Application of these lasers in THz metrology can suffer from several drawbacks like coupling between the modes, strong amplitude variations, low tuning capabilities, or a complicated growth process. We discuss the impact of these points for THz measurements and present a simple monolithic dual colour laser which can be used for material characterisations.

Detection of backside coupled propagating surface plasmon resonance on the sidewall of a wafer

We proposed a surface plasmon resonance (SPR) sensor structure that utilized a glass wafer with a diffraction grating and an n-type silicon piece bonded near the SPR coupling site. This configuration enabled surface plasmon excitation from the back of the substrate without the unwanted interaction between the excitation light and the sample, and electrical detection of the SPR response by a 0.7-eV Schottky barrier at the Au/n-Si interface formed on the sidewall of the silicon piece was achieved. Experimental evaluation of the surface plasmon coupling performance was conducted, showing clear peaks in the photocurrent for various wavelengths in the NIR-II window, ranging from 1100 to 1300 nm. The device’s ability to detect propagating surface plasmons as a photocurrent was confirmed; the results indicated a consistent trend with theoretical and numerical calculations. Since the device was composed of a glass substrate, the use of wavelengths shorter than the near-infrared wavelength was possible, including visible wavelengths where the optical absorption by water is negligible. Thus, our proposed sensor provides a compact and efficient solution for SPR sensing in aqueous solutions.

Incremental shape measurement with fiber Bragg gratings in a multi-core fiber for three-dimensional paths.

A multi-core fiber (MCF) provides a compact solution for three-dimensional (3D) shape measurement. In this Letter, an incremental shape measurement method for 3D paths is proposed, using an MCF based on fiber Bragg gratings (FBGs). A few FBG sets can iteratively provide plenty of strain information about the 3D path during navigation. The overall continuities of the curvature and torsion are improved based on intensive strain calculations. Meanwhile, the transformation matrix algorithm is used to reconstruct the shape of 3D paths. Dynamic measurement experiments of a seven-core fiber with two FBG sets are carried out to verify the incremental shape measurement method. This method shows a great performance of the different paths, with a maximum incremental position error of 4.68%.

A High-Sensitivity Fiber Biosensor Based on PVDF-Excited Surface Plasmon Resonance in the Terahertz Band

In this paper, a D-type photonic crystal fiber (PCF) with Zeonex material as the substrate and polyvinylidene fluoride (PVDF) material as the surface plasmon resonance (SPR) excitation layer is proposed for biosensing in the terahertz (THz) band. Analyzed with a finite element method, the proposed biosensor has shown excellent sensing properties for analyte refractive indices ranging from 1.32 to 1.45. With a maximum sensor resolution of 8.40 × 10−7 refractive index unit (RIU) and a figure of merit of 39.42 RIU−1, the maximum wavelength sensitivity and amplitude sensitivity can reach 335.00 μm/RIU and −66.01 RIU−1, respectively. A ±2% fabrication tolerance analysis is also performed on the biosensor to prove its practical feasibility. We conclude that our proposed PCF biosensor utilizing PVDF-excited SPR can provide high sensitivity, and thus a compact, label-free, and convenient solution for biomedical liquid sensing in the THz band.

Deep Bayesian Quantization for Supervised Neuroimage Search.

Neuroimage retrieval plays a crucial role in providing physicians with access to previous similar cases, which is essential for case-based reasoning and evidence-based medicine. Due to low computation and storage costs, hashing-based search techniques have been widely adopted for establishing image retrieval systems. However, these methods often suffer from nonnegligible quantization loss, which can degrade the overall search performance. To address this issue, this paper presents a compact coding solution namely Deep Bayesian Quantization (DBQ), which focuses on deep compact quantization that can estimate continuous neuroimage representations and achieve superior performance over existing hashing solutions. Specifically, DBQ seamlessly combines the deep representation learning and the representation compact quantization within a novel Bayesian learning framework, where a proxy embedding-based likelihood function is developed to alleviate the sampling issue for traditional similarity supervision. Additionally, a Gaussian prior is employed to reduce the quantization losses. By utilizing pre-computed lookup tables, the proposed DBQ can enable efficient and effective similarity search. Extensive experiments conducted on 2, 008 structural MRI scans from three benchmark neuroimage datasets demonstrate that our method outperforms previous state-of-the-arts.

Design and Assessment of Unified Multi-Input Multi-Output Converter Based Islanded Microgrid for Rural and Remote Areas

—This paper addresses an islanded microgrid (MG) for rural and remote areas (RRAs) that aims to provide reliable electricity, considering the challenges posed by geographical constraints on solar power generation. Solutions and development for specific applications in RRA, can’t form MG to fulfill all needs of RRA at once because their integration creates circulating currents, power losses & compromised power quality. To overcome this, a robust, techno-economical, low-maintenance all-in-one single-synchronized compact solution has been introduced for establishing and upgrading existing islanded MGs for RRA. The proposed solution is Unified Multi-Input Multi-Output (U-MIMO) based islanded MG (MMG), designed to support multi-location PV arrays catering to various loads. It has three-phase four-wire system, battery management system (BMS) and supports DC load/E-Vehicles. The objectives are to enhance the utilization of solar power, enable controllability of power generation & daily load demands and facilitate ease of implementation. The experimental results demonstrate that U-MIMO is effectively compatible with all types of loads (AC/DC), allowing the integration of PV arrays across multiple locations even in unbalanced irradiance conditions while maintaining the total harmonic distortion (THD) below 5%. This showcases the versatility and reliability of the proposed U-MIMO-based MMG for sustainable electricity generation in RRA.

Injection-locked soliton microcomb against temporal drifting

The soliton microcomb offers a unique and compact solution for photonics applications. However, the microcomb is suffering from the perturbations arising from complex higher-order effects such as self-steepening and third-order dispersion, leading to the temporal drift of soliton and the deviation of repetition rate. It is unfavorable to the stability in time and frequency domains. In this work, we numerically and theoretically demonstrate that the injection-locking scheme can effectively eliminate the soliton temporal drift and repetition rate deviation caused by complex higher-order effects. The mechanism of eliminating drift and deviation is explained, and the theoretically predicted stable soliton temporal position agrees well with the simulation. The modulation depth plays a key role in suppressing drift, and an experimental guide for adjusting modulation depth is given. This work enriches soliton dynamics under complex higher-order effects and provides a scheme to improve the stability and controllability of microcombs.