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Large active-area superconducting nanowire single-photon detectors (SNSPDs) coupled with multimode fibers (MMFs) can provide high light-gathering capacity, which is essential for free-space detection applications in photon-starved regimes. However, MMF-coupled SNSPDs often suffer from large system dark count rates (DCRsys) over kHz due to blackbody radiation of the MMF at room temperature. Such large DCRsys would significantly degrade signal-to-noise ratio (SNR) of the receiving system. This paper reports an MMF-coupled large-active-area SNSPD system with low DCRsys by using a homemade cryogenic MMF filter bench. The filter bench, which consists of lenses and optical filters, can provide a high transmittance of about 80% at the central wavelength of the passband (1550 ± 12.5 nm) and a wide blocking range from 500 nm to over 6000 nm at 40 K. With using the filter bench, the DCRsys of an MMF-coupled 9-pixel SNSPD array with an active area of 50 μm in diameter is greatly suppressed by 23 dB with 1 dB loss of system detection efficiency (SDE). The detector demonstrates an SDE of 51% at a DCRsys of 100 Hz for 1550 nm photons. Thus, SNR of the detector is enhanced by about 160 times and the noise equivalent power is improved to 3×10-19 W/Hz1/2.

Increasing the count rate (CR) is one of the key issues in the development of superconducting nanowire single-photon detectors (SNSPDs) for different applications. This study aims to design, fabricate, and analyze a 16-pixel interleaved nanowire SNSPD array, which exhibits a system detection efficiency (SDE) of 72% and a dark CR of 100 Hz at a low-photon-flux limit and a wavelength of 1550 nm. By exploiting the increased pixel number and reduced dead time (

We report a compact, scalable, and high-performance superconducting nanowire single-photon detector (SNSPD) array by using a multichannel optical fiber array-coupled configuration. For single pixels with an active area of 18 µm in diameter and illuminated at the telecom wavelength of 1550 nm, we achieved a pixel yield of 13/16 on one chip, an average system detection efficiency of 69% at a dark count rate of 160 cps, a minimum timing jitter of 74 ps, and a maximum count rate of ∼ 40 M c p s . The optical crosstalk coefficient between adjacent channels is better than − 60 d B . The performance of the fiber array-coupled detectors is comparable with a standalone detector coupled to a single fiber. Our method is promising for the development of scalable, high-performance, and high-yield SNSPDs.

Background The overall genetic distribution and divergence of cloned genes among bread wheat varieties that have occurred during the breeding process over the past few decades in Ningxia Province, China, are poorly understood. Here, we report the genetic diversities of 44 important genes related to grain yield, quality, adaptation and resistance in 121 Ningxia and 86 introduced wheat cultivars and advanced lines. Results The population structure indicated characteristics of genetic components of Ningxia wheat, including landraces of particular genetic resources, introduced varieties with rich genetic diversities and modern cultivars in different periods. Analysis of allele frequencies showed that the dwarfing alleles Rht-B1b at Rht-B1 and Rht-D1b at Rht-D1, 1BL/1RS translocation, Hap-1 at GW2-6B and Hap-H at Sus2-2B are very frequently present in modern Ningxia cultivars and in introduced varieties from other regions but absent in landraces. This indicates that the introduced wheat germplasm with numerous beneficial genes is vital for broadening the genetic diversity of Ningxia wheat varieties. Large population differentiation between modern cultivars and landraces has occurred in adaptation genes. Founder parents carry excellent allele combinations of important genes, with a higher number of favorable alleles than modern cultivars. Gene flow analysis showed that six founder parents have greatly contributed to breeding improvement in Ningxia Province, particularly Zhou 8425B, for yield-related genes. Conclusions Varieties introduced from other regions with rich genetic diversity and landraces with well-adapted genetic resources have been applied to improve modern cultivars. Founder parents, particularly Zhou 8425B, for yield-related genes have contributed greatly to wheat breeding improvement in Ningxia Province. These findings will greatly benefit bread wheat breeding in Ningxia Province as well as other areas with similar ecological environments.

Generally, a superconducting nanowire single-photon detector (SNSPD) is composed of wires with a typical width of ~100 nm. Recent studies have found that superconducting strips with a micrometer-scale width can also detect single photons. Compared with the SNSPD, the superconducting microstrip single-photon detector (SMSPD) has smaller kinetic inductance, higher working current, and lower requirement in fabrication accuracy, providing potential applications in the development of ultra-large active area detectors. However, the study on SMSPD is still in its infancy, and the realization of its high-performance and practical use remains an opening question. This study demonstrates a NbN SMSPD with a saturated system detection efficiency (SDE) of ~92.2% at a dark count rate of ~200 cps, a polarization sensitivity of ~1.03, and a minimum timing jitter of ~48 ps, at the telecom wavelength of 1550 nm when coupled with a single mode fiber and operated at 0.84 K. Furthermore, the detector's SDE is over 70% when operated at a 2.1-K closed-cycle cryocooler., 10 pages,7 figures, 2 tables

Background: The overall genetic distribution and divergences for cloned genes among wheat varieties that occurred during the breeding process of the past few decades in Ningxia province of China are poorly understood. Here we report the genetic diversities of 44 important genes underpinning grain yield, quality, adaptation and resistance in 121 Ningxia and 86 introduced wheat cultivars and advanced lines.Results: Population structure indicated characteristics of genetic components of Ningxia wheats including landraces of particular genetic resources, introduced varieties with rich genetic diversities and modern cultivars in different times. Analysis of allele frequencies showed that dwarfing alleles Rht-B1b at Rht-B1 and Rht-D1b at Rht-D1 , 1BL/1RS translocation, Hap-1 at GW2-6B and Hap-H at Sus2-2B are present very frequently in Ningxia modern cultivars and introduced varieties from other regions, but absent in landraces, indicating that the introduced wheat germplasm with numerous beneficial genes are vital for broadening genetic diversities of Ningxia wheat varieties. Large population differentiation occurred at adaptation genes between modern cultivars and well-adapted landraces. Founder parents have excellent allele combinations of important genes with a higher number of favorable alleles compared with modern cultivars. The gene flows manifested that six founder parents greatly contributed to breeding improvement in Ningxia province, in particular Zhou 8425B for yield related genes.Conclusions: These results will greatly benefit for wheat breeding in Ningxia province and other areas with similar ecological environments.

Typhoon disaster can result in wind farms shutdown. With the large-scale integration of wind farms in power system, the wind farms shutdown may affect the operation of power system, causing the power shortage and voltage violation. In this paper, a shutdown risk assessment method is proposed to evaluate the risk of wind farms operation under typhoon disaster. Firstly, the distribution of forecast error of wind power under typhoon conditions is analyzed according to the historical data and is established as T distribution. Next, the real-time shutdown probability of wind farms is generated by the known cumulative error distribution. Then, the shutdown cost of wind farms are expressed by the cost of shedding load after wind power exiting, which is solved by particle swarm optimization method. Finally, the adjusted IEEE-33 node system with wind farms are adopted to verify the effectiveness of proposed method.

Most of the small-size hydropower stations are runoff hydropower stations and their output is determined by the upstream water supply. Consequently, the rainfall brought by typhoons will lead to the increment of runoff, increasing the output of small-size hydropower stations. The uncertain increment of the output of small-size hydropower stations will bring adverse effects on the security of power system, such as the voltage over-limit and the power overload of transmission lines. In this paper, a risk assessment method is proposed to assess the shutdown risk of small-size hydropower station under typhoon disaster. Firstly, Monte Carlo Method is employed to calculate the probabilistic load flow of power system with small-size hydropower station and the probability of node voltage over-limit and branch power overload is set to be the shutdown probability of small-size hydropower station. Secondly, the cost of load shedding which is optimized by Adaptive Particle Swarm optimization (APSO) algorithm is set to be the shutdown cost of small-size hydropower station. Finally, the IEEE-33 bus system is used to assess the shutdown risk of small-size hydropower station under typhoon disaster.

Frequent typhoons may threaten the operation security of coastal power system with high wind power integration, inducing severe wind power rapid climbs and line active power violations. Aiming at the phenomenon and problems in real typhoon disasters, this paper proposes a multisource coordinated dispatching strategy for high wind power penetration system under typhoon environment. In this paper, a wind farm output model considering wind speed is established. Besides, the profiles and fitting effects of different wind fields are compared. In the end of this paper, a multi-objective security constrained economic dispatch strategy during typhoons is proposed. The analysis of the regional system validates that the proposed dispatch strategy is feasible for the security improvement of the power system during typhoons.

The battery energy storage station (BESS) is developing from the demonstration project to the stage of business promotion. Due to the unsound Economic benefit evaluation, which restricts the large-scale promotion and construction of BESS. This paper establishes the life cycle cost and income model of BESS and uses the dynamic investment payback period, net present value (NPV), internal rate of return (IRR) and other economic indicators to analyze the economy of offshore wind power with BESS in peak shaving auxiliary service market. At the same time, aiming at stimulating the enthusiasm of the wind farm to allocate energy storage, we studied the improvement of the market regulation rules and government subsidies. The research results can provide an engineering economic reference for the investment decision of BESS and the government to guide the development of energy storage.

Superconducting nanowire single-photon detectors (SNSPDs) with high system detection efficiency (SDE) would enable remarkable experiments in quantum information processing. However, realizing a NbN SNSPD with saturated intrinsic detection efficiency (IDE) that retains high SDE at near-infrared wavelengths is challenging, due to the high critical temperature of NbN. This study uses defect engineering by helium-ion irradiation to enhance the IDE of NbN SNSPDs to saturation without sacrificing SDE. This technique also allows direct comparison of irradiation-induced changes in detector performance, making it a useful tool for studying the physics of superconducting devices.

Wind power generation systems include slow-changing mechanical systems such as wind turbines and drivelines, as well as fast-changing power electronic controls and protection of electrical systems such as surveys, hybrid systems with multiple time scales. It is very important to develop the transient model of wind power with high accuracy to meet the stability analysis of power system as much as possible to meet the actual operating characteristics of wind turbine. This paper focuses on the need of system stability analysis after large-scale wind power integration. Based on the accurate reflection of the failure-tracing wind farm model of wind turbine under grid fault, this paper evaluates the system security and stability after a large number of wind power grid-connected.

Superconducting nanowire single-photon detectors (SNSPDs) have attracted remarkable interest for visible and near-infrared single-photon detection due to their outstanding performance. However, conventional SNSPDs are generally used as binary photon-counting detectors. Another important characteristic of light, i.e., polarization, which can provide additional information of the object, has not been resolved using the standalone SNSPD. In this work, we present a first prototype of the polarimeter based on a four-pixel superconducting nanowire array, capable of resolving the polarization state of linearly-polarized light at the single-photon level. The detector array design is based on a division of focal plane configuration in which the orientation of each nanowire division (pixel) is offset by 45°. Each single nanowire pixel operates as a combination of a photon detector and almost linear polarization filter, with an average polarization extinction ratio of ∼10. The total system detection efficiency of the array is ∼1% at a total dark count rate of 680 cps, with a timing jitter of 126 ps, when the detector array is free-space coupled and illuminated with 1550-nm photons. The mean errors of the measured angle of polarization and degree of linear polarization were about -3° and 0.12, respectively. Furthermore, we successfully demonstrated polarization imaging at low-light level using the proposed detector. Our results pave the way for the development of a single-photon sensitive, fast, and large-scale integrated polarization polarimeter or imager. Such detector may find promising application in photon-starved polarization resolving and imaging with high spatial and temporal resolution.

At present, China has overtaken the United States to become the world’s largest new energy vehicle market. Due to differences in developmental trajectory, developmental mode, and charging standards, China and the U.S. have common interests and the foundation for cooperation, which can work together for a win-win development. Charging interoperability is the basis for ensuring charging safety and interchangeability of electric vehicles. This study examined and compared the differences between China and the U.S. in the standards for conductive AC charging of electric vehicles. The requirements for a control pilot circuit, proximity circuit, current capacity, and charging-state transition timing were analysed. Hierarchical and layered interoperability test cases based on GB/T 34657 and SAE J2953 series were presented. A dual interface interoperability test system was constructed and used to verify the test method rationale. The results provided a mutual inspection solution for AC charging equipment between China and the U.S. and accelerated global application and promotion of the electric vehicle industry.

The implementation of quantum information technologies requires the development of integrated quantum chips. Femtosecond laser direct writing (FLDW) waveguides and superconducting nanowire single-photon detectors (SNSPDs) have been widely applied in integrated quantum photonic circuits. In this work, a novel FLDW waveguide-coupled SNSPD was designed and realized by integrating FLDW waveguides and conventional SNSPDs together. Through a COMSOL simulation, a waveguide end face-nanowire optical coupling structure was designed and verified. The simulation results showed that the FLDW waveguide-coupled SNSPD device, which had a target wavelength of 780 nm, can achieve 87% optical absorption. Then the preparation process of the FLDW waveguide-coupled SNSPD device was developed, and the fabricated device achieved a system detection efficiency of 1.7% at 10 Hz dark count rate. Overall, this method provides a feasible single-photon detector solution for future on-chip integrated quantum photonic experiments and applications.

With the rapid development of science and technology, human sciences is entering the information age, information technology has a profound influence to the reform of school management. Modernization school must have Modern management facility, equipment. The level of information management is becoming one of the important factors for measuring the aggregate level of the school, but also an important symbol of modern standards school management. This article describes to take the campus card system as a platform to achieve all the people-oriented digital management, from the campus environment, resources and activities. The campus card system can realize “one card in hand, around the campus,” to meet the needs and purpose of digitized campus.

Count rate (CR) is one of the key parameters of superconducting nanowire single-photon detectors (SNSPDs). The practical SNSPDs usually have a CR of a few MHz to a few tens of MHz owing to the large kinetic inductance originating from the long nanowire, which is necessary for effectively coupling the photons. A feasible approach to decrease the kinetic inductance and consequently increase the detection speed is to replace a long single nanowire with multiple individual nanowires in an array. In this study, we report an SNSPD of nine interleaved nanowires with 70% system detection efficiency (SDE) and 200 Hz dark count rate at the low-photon-flux limit of 1550 nm. Owing to the small dead time (

Superconducting nanowire single-photon detectors (SNSPDs) with both high system detection efficiency (SDE) and low dark count rate (DCR) play significant roles in quantum information processes and various applications. The background dark counts of SNSPDs originate from the room temperature blackbody radiation coupled to the device via a fiber. Therefore, a bandpass filter (BPF) operated at low temperature with minimal insert loss is necessary to suppress the background DCR. Herein, a low-loss BPF integrated on a single-mode fiber end-face was designed, fabricated and verified for the low temperature implement. The fiber end-face BPF was featured with a typical passband width about 40 nm in the 1550 nm telecom band and a peak transmittance of over 0.98. SNSPD with high SDE fabricated on a distributed Bragg reflector was coupled to the BPF. The device with such a BPF showed an SDE of 80% at a DCR of 0.5 Hz, measured at 2.1 K. Compared the same device without a BPF, the DCR was reduced by over 13 dB with an SDE decrease of