Compact Generation Research Articles

Development of air-cooled compact Organic Rankine Cycle power generation technology utilizing waste heat

As the effective utilization method of unused heat energy between 100 and 300 degree-C in the industrial sector, Organic Rankine Cycle (ORC) was selected from the viewpoint of high efficiency. The prototype of air-cooled compact ORC electric power generation system for 1kW class was evaluated in variation of the ambient temperature of condenser and the inlet temperature of expander. In the experimental results, at the expander inlet temperature of 175 degree-C and the ambient temperature of 20 degree-C for condenser, the generated power by the expander is 1,027W and the gross power generation efficiency is 10.3%. The net power generation efficiency, considering the input power of auxiliary equipment such as pumps and fans, is 9.0%. In the result of energy balance analysis, power consumptions of the pump and the fan are small and almost of the generated power is effectively available.

Perfect complexes on algebraic stacks

We develop a theory of unbounded derived categories of quasi-coherent sheaves on algebraic stacks. In particular, we show that these categories are compactly generated by perfect complexes for stacks that either have finite stabilizers or are local quotient stacks. We also extend Toën and Antieau–Gepner’s results on derived Azumaya algebras and compact generation of sheaves on linear categories from derived schemes to derived Deligne–Mumford stacks. These are all consequences of our main theorem: compact generation of a presheaf of triangulated categories on an algebraic stack is local for the quasi-finite flat topology.

On-chip generation of high-dimensional entangled quantum states and their coherent control.

Optical quantum states based on entangled photons are essential for solving questions in fundamental physics and are at the heart of quantum information science. Specifically, the realization of high-dimensional states (D-level quantum systems, that is, qudits, with D > 2) and their control are necessary for fundamental investigations of quantum mechanics, for increasing the sensitivity of quantum imaging schemes, for improving the robustness and key rate of quantum communication protocols, for enabling a richer variety of quantum simulations, and for achieving more efficient and error-tolerant quantum computation. Integrated photonics has recently become a leading platform for the compact, cost-efficient, and stable generation and processing of non-classical optical states. However, so far, integrated entangled quantum sources have been limited to qubits (D = 2). Here we demonstrate on-chip generation of entangled qudit states, where the photons are created in a coherent superposition of multiple high-purity frequency modes. In particular, we confirm the realization of a quantum system with at least one hundred dimensions, formed by two entangled qudits with D = 10. Furthermore, using state-of-the-art, yet off-the-shelf telecommunications components, we introduce a coherent manipulation platform with which to control frequency-entangled states, capable of performing deterministic high-dimensional gate operations. We validate this platform by measuring Bell inequality violations and performing quantum state tomography. Our work enables the generation and processing of high-dimensional quantum states in a single spatial mode.

Wavelet analysis of light emission signals in laser beam welding

This paper introduces a compact, robust, and versatile generation of a laser processing head coupled with a single-mode Ytterbium source StarFiber 150 P which not only is used in a wide range of laser material processing applications but also enables in situ and real-time quality control in production lines. In this study, the effect of power density on the weld quality of bead on plate in a SHADOW (Stepless high speed accurate and discrete one pulse welding) welding process was considered. Furthermore, the co-axial back reflected/emitted light from the process zone was measured using three optical sensors; each one measures the light emission in a certain waveband (450–850, 1000–1200, and 1250–1700 nm). From these sensors, the recorded signals were first used as benchmarks to correlate with the weld quality features and defects. Discrete wavelet transform has been used to analyze the signal within the time–frequency domain. The detail signals at different decomposition levels disclosed information with regard to the type (mode) and dynamics of welding process. Accordingly, the deep penetration welding (keyhole) was confidentially distinguished from the shallow (conduction) welding mode. Several defects such as process instabilities (high fluctuations in the keyhole dynamics), formation, and collapse of the keyhole, as well as the lack of penetration, were detected from the corresponding signal signatures. In addition, this information permits us to locate the defect/transition site through the in situ and real-time quality control of the process in production lines. In contrast, porosity and cracks could not be sensed.

Compact Generation of Airy Beams with C‐Aperture Metasurface

A novel method to launch finite power Airy beams based on a metasurface is presented. By tailoring the amplitude and phase of the transmitted fields from a metallic C‐aperture array, launching Airy beams is achieved in free space. The amplitude and phase of the Airy beam profile can be mapped and tailored by tuning only the tilt angles of the aperture. This structure has multifrequency characteristics, which facilitates Airy beam steering because the trajectory of Airy beams is dependent on the wavelength. In addition, the design method can generate Airy beams which have a very compact main lobe (≈2 µm). Computational and experimental results show that proposed metasurface can overcome some limitations of the traditional methods to generate Airy beams. The results can be used for potential applications in integrated optics, beam shaping, biosensing, and next‐generation holography.

Compact and Flexible Dual-Wavelength Laser Generation in Coaxial Diode-End-Pumped Configuration

A novel coaxial diode-end-pumping configuration with combined two laser crystals was proposed for simultaneous, compact, and flexible dual-wavelength laser generation. Theoretical simulations showed that by balancing the gain in both laser crystals by varying the pump focusing depth or pump wavelength, the power ratio for each wavelength could be tuned for either continuous wave or Q-switched operation, and the time interval between two pulses at different wavelengths in Q-switched mode was also tunable. Experimental verifications were performed, demonstrating coincident conclusions. As there was no gain competition between two wavelengths, the output characteristics were much more stable than dual-wavelength generation in a single-laser crystal. It is believed that this is a feasible and promising method for generating dual-wavelength laser for applications of spectroscopy, precision measurement, nonlinear optical frequency conversion to terahertz wave, and so on.

117 Gbits/s Quantum Random Number Generation With Simple Structure

We propose and implement a simple and compact quantum random number generation (QRNG) scheme based on the quantum phase fluctuations of a DFB laser. The distribution probability of the experimentally measured data fits well with the simulation result, got from the theoretical model we established. Min-entropy estimation and Toeplitz-hashing randomness extractor are used to obtain the final random bit. The proposed approach has advantages not only in simple structure but also in high random bit generation rate. As a result, 502 Gbits/s random bits generation speed can be obtained, which is much higher than previous similar schemes. This approach offers a possibility to promote the practical application of QRNG.

高効率小型オーガニックランキンサイクル発電技術の開発

As the effective utilization method of unused heat energy between 100 and 300 degree-C in the industrial field, Organic Rankine Cycle(ORC) was selected from the viewpoint of high efficiency. The prototype of air-cooled compact ORC power generation system for 1kWe class was evaluated in comparison of the two working fluids, HFO-1336mzz(Z) and HFC-365mfc. The GWP of HFO-1336mzz(Z) is about 99.7% lower than that of HFC-365mfc. In the experimental results using HFO-1336mzz(Z), the generated power by the expander is 1,000W and the gross power generation efficiency is 10.5%. The gross power generation efficiency using HFO-1336mzz(Z) is equivalent to that using HFC-365mfc.

High efficiency cross-polarized wave filter for non-vacuum transmission

Development of high-peak power laser system encounters difficulties in producing the pulses with high temporal contrast. To increase the pulse temporal contrast ratio, a nonlinear filter based on crossed-polarized wave (XPW) generation is proposed. The XPW generation relies on a third-order nonlinear process occurring in a nonlinear medium, such as barium fluorite (BaF2) crystal. The XPW process is quite straightforward:a linearly polarized laser pulse is focused on BaF2 crystal positioned between two orthogonally polarizers, high power main pulses due to nonlinear polarization rotation can pass through the second polarizer, while low power unconverted pre-and post-pulses are filtered by the second polarizer. With the XPW technique, pulse contrast can be enhanced by several orders of magnitude. Furthermore, XPW spectrum can be broaden by a factor with respect to the initial spectrum. This efficient pulse cleaner presents many advantages and has proved to be a simple and reliable pulse filter operating in a double chirped pulse amplification system. Most of previous XPW experiments utilize short focal systems or work off focus due to an intensity limit in the crystal (BaF2). These drawbacks result in a lower conversion efficiency (lower than 10%) when using a single crystal. Dual crystal setup is capable of achieving efficiency more than 20%, yet the configuration restricts the crystal separation to a millimeter level. The use of long focus lens in the XPW device is capable of reaching higher efficiency, with BaF2 crystal positioned in the focal plane. Hence for milljoule pulses, the setup distance increases to tens of meters, resulting in a complicated system and cumbersome configuration. Considering these limitations, a compact, highly efficient and stable XPW generation using dual-lens system suitable for non-vacuum transmission is presented. The measured nonlinear accumulated phase shows little deterioration of pulse quality. With a compact dual lens system, we realize an excellent XPW conversion of above 22% (internal efficiency of 30%) with using double BaF2 crystals, while a femtosecond laser pulse can experience a spectrum broadening up to a factor of 1.78. The dual-lens configuration overcomes the crystal separation limit, and conversion efficiency exceeds 20% for a crystal separation from 13 cm to 22 cm, which is conducible to flexibility and robustness. The stability for the setup to generate shorter pulses with very high contrast or compensate for spectral gain narrowing in the preamplifier is ensured due to the dual-lens focusing system.

Knowledge-Based Compact Disease Models: A Rapid Path from High-Throughput Data to Understanding Causative Mechanisms for a Complex Disease.

High-throughput profiling of human tissues typically yields the gene lists composed of a variety of more or less relevant molecular entities. These lists are riddle by false positive observations that often obstruct generation of mechanistic hypothesis that may explain complex phenotype. From general probabilistic considerations, the gene lists enriched by the mechanistically relevant targets can be far more useful for subsequent experimental design or data interpretation. Using Alzheimer's disease as example, the candidate gene lists were processed into different tiers of evidence consistency established by enrichment analysis across subdatasets collected within the same experiment and across different experiments and platforms. The cutoffs were established empirically through ontological and semantic enrichment; resultant shortened gene list was reexpanded by Ingenuity Pathway Assistant tool. The resulting subnetworks provided the basis for generating mechanistic hypotheses that were partially validated by mined experimental evidence. This approach differs from previous consistency-based studies in that the cutoff on the Receiver Operating Characteristic of the true-false separation process is optimized by flexible selection of the consistency building procedure. The resultant Compact Disease Models (CDM) composed of the gene list distilled by this analytic technique and its network-based representation allowed us to highlight possible role of the protein traffic vesicles in the pathogenesis of Alzheimer's. Considering the distances and complexity of protein trafficking in neurons, it is plausible to hypothesize that spontaneous protein misfolding along with a shortage of growth stimulation may provide a shortcut to neurodegeneration. Several potentially overlapping scenarios of early-stage Alzheimer pathogenesis are discussed, with an emphasis on the protective effects of Angiotensin receptor 1 (AT-1) mediated antihypertensive response on cytoskeleton remodeling, along with neuronal activation of oncogenes, luteinizing hormone signaling and insulin-related growth regulation, forming a pleiotropic model of its early stages. Compact Disease Model generation is a flexible approach for high-throughput data analysis that allows extraction of meaningful, mechanism-centered gene sets compatible with instant translation of the results into testable hypotheses.

84-, 100-, and 107-GBd PAM-4 Intensity-Modulation Direct-Detection Transceiver for Datacenter Interconnects

We report on an ultrahigh-speed PAM-based IM/DD optical subsystem featuring compact signal generation and tractable digital-processing complexity. The proposed transceiver is based on two main technologies: an InP DHBT selector power DAC for electrical signal generation, and a complexity-optimized receiver processing chain. We show how the complexity of the feed-forward equalizer can be considerably reduced by stacking a <3-symbol memory sequence estimator. Finally, we experimentally demonstrate successful signal recovery for 107-GBd PAM-4 in back-to-back configuration, and after 500 m and 1 km of transmission over standard single-mode fiber for 100- and 84-GBd PAM-4 configuration, respectively. A power-budget margin above 2 dB is attained in all cases.

Property Fℓq implies property Fℓp for 1 < p < q < ∞

It is known that for σ-compact groups Kazhdan's Property (T) is equivalent to Serre's Property FH. Generalized versions of those properties, called properties (TB) and FB, can be defined in terms of the isometric representations of a group on an arbitrary Banach space B. Property FB implies (TB).It is known that a group with Property (Tℓp) shares some properties with Kazhdan's groups, for example compact generation and compact abelianization. Moreover in the case of discrete groups, Property (Tℓp) implies Lubotzky's Property (τ).In this paper we prove that in the case of discrete groups and ℓp(N) spaces, for 1<p<q<∞,p≠2, Property Fℓq implies Property Fℓp.

Compact and portable 100-GHz microresonator-based optical frequency comb generation system for dense wavelength division multiplexing fiber optic communication

A compact and portable microresonator-based optical frequency comb generation system was developed to provide an array of multiwavelength laser sources for dense wavelength division multiplexing (DWDM) fiber optic communication. The reported comb generation system was capable of producing comb lines after 7 km of travel without environmental control, indicating the effectiveness of the packaging. The comb spacing is about 98.3 GHz (i.e., ∼0.79 nm around 1553 nm), thus the comb line frequencies coincide nicely with 100-GHz DWDM channel frequencies, assuming the suggested channel bandwidth is 0.3 nm. The quality of selected comb lines was evaluated individually based on error vector magnitude (EVM) measurements along with RF spectrum measurements. An average EVM value observed is as low as 3.8%, close to typical EVM values of less than 3% used for fiber optic communication.

Bit selection via walks on graph for hash-based nearest neighbor search

Recently hashing with multiple tables has become attractive in many real life applications, owing to its theoretical guarantee and practical success. To pursue the desired performance, usually great efforts are required on the hashing algorithm design for the specified scenario. Hash bit selection serves as a general method that can provide satisfying performance for different scenarios by utilizing existing hashing algorithms. In this paper, a novel bit selection framework via walks on graph is proposed to support both compact hash code generation and complementary hash table construction. It formulates the selection problem as the subgraphs discovery on an edge- and vertex-weighted graph, where the most desired subset corresponds to the frequently visited ones (bits/tables) in a Markov process. The framework is unified and compatible with different hashing algorithms. For compact code generation, it selects the most independent and informative hash bits using the Markov process over the candidate bit graph. For complementary hash table construction, it exploits the hierarchical authority relations among all candidate bits and separates them into a number of bit subsets as the candidate tables, from which multiple complementary hash tables can be efficiently selected. Experiments are conducted for two important selection scenarios, i.e., hashing using different hashing algorithms and hashing with multiple features. The results indicate that our proposed selection framework achieves significant performance gains over the naive selection methods under different scenarios.

Dimensionality reduced local directional pattern (DR-LDP) for face recognition

Local Directional Pattern (LDP) is a descriptor used for face recognition. It assigns a code for each pixel in the image, and the resultant LDP-encoded image is divided into regions for which each a histogram is generated. The histogram bins of all the regions are concatenated to form the final descriptor. In contrast to LDP, a dimensionality reduced local directional pattern (DR-LDP) is proposed in this paper. The proposed descriptor computes single code for each block by X-ORing the LDP codes obtained in a single block. During the process, restructuring of the patterns is done by slightly modifying the LDP coding pattern constraints. The significance of DR-LDP is the compact code generation for efficient face recognition. The experiments were carried out on standard databases like FERET, extended YALE-B database and ORL. The resultant DR-LDP descriptor provided better recognition rates, outperforming the existing local descriptor-based methods and proving its efficacy. The compact code can be further extended to provide biometric security.

Robust and compact entanglement generation from diode-laser-pumped four-wave mixing

Four-wave-mixing processes are now routinely used to demonstrate multi-spatial-mode Einstein-Podolsky-Rosen entanglement and intensity difference squeezing. Diode-laser-pumped four-wave mixing processes have recently been shown to provide an affordable, compact, and stable source for intensity difference squeezing, but it was unknown if excess phase noise present in power amplifier pump configurations would be an impediment to achieving quadrature entanglement. Here, we demonstrate the operating regimes under which these systems are capable of producing entanglement and under which excess phase noise produced by the amplifier contaminates the output state. We show that Einstein-Podolsky-Rosen entanglement in two mode squeezed states can be generated by a four-wave-mixing source deriving both the pump field and the local oscillators from a tapered-amplifier diode-laser. This robust continuous variable entanglement source is highly scalable and amenable to miniaturization, making it a critical step toward the development of integrated quantum sensors and scalable quantum information processors, such as spatial comb cluster states.

Completeness and Compact Generation in Partially Ordered Sets

Completeness and Compact Generation in Partially Ordered Sets

Modeling of two‐pump optical frequency comb generation in monolithic silicon nitride ring resonator

ABSTRACTThe two‐pump Four‐Wave‐Mixing (FWM) in the ring resonator promises more agile compact frequency comb generation than the traditional singe‐pump scheme regarding the convenient tuning of comb line space by modifying the two pumps’ space. The silicon‐nitride‐ring‐resonator‐based optical frequency comb generation system input with two pumps for the parametric process is simulated by an iterative process relying on the split‐step Fourier method. The influences of the coupling coefficient and pumps’ frequencies on the comb spanning are explained in terms of Q factor and resonance condition of the ring. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:919–921, 2016

On Optimization-Based ATPG and Its Application for Highly Compacted Test Sets

Test compaction is an important aspect in the post-production test since it is able to reduce the test data and the test costs, respectively. Current automatic test pattern generation (ATPG) methods treat all faults independently from each other which limits the test compaction capability. We propose a new optimization satisfiability (SAT)-based ATPG for compact test set generation with high fault coverage as well as a new retargeting stage for test set reduction. The ATPG is based on a novel multiple-target test generation formulation using optimization techniques. Robust SAT-based solving algorithms are leveraged to determine compatible fault groups which can be detected by the same test. The proposed technique can be used during initial compact test generation as well as a post-process to increase the compactness of existing test sets, e.g., generated by commercial tools, in an iterative manner. Experimental results show that the proposed SAT-based approach is able to produce highly compacted test sets with high fault coverage for stuck-at as well as transition faults. The approach is able to produce lower pattern counts than a commercial ATPG tool. For one industrial circuit, the test set size can even be reduced down to 26% of the size generated by a commercial ATPG tool.

A reliable, compact, and repetitive-rate high power microwave generation system.

A compact high power microwave (HPM) generation system is described in this paper. The main parts of the HPM system are a Marx generator with a pulse forming line and a magnetron with diffraction output. The total weight and length of the system are 250 kg and 120 cm, respectively. The output microwave power of the HPM system at 550 kV of applied voltage and 0.33 T of magnetic field reaches 1 GW at 2.32 GHz of central frequency with 38 ns of pulse duration, 23% of power conversion efficiency, and Gaussian radiation pattern. In the bursts operation, both time and amplitude jitters are less than 4 ns and lower than 1.5 dB, respectively.