Active User and Data Detection for Uplink Grant-free NOMA Systems

This paper proposes some low complexity algorithms for active user detection(AUD),channel estimation(CE)and multi-user detection(MUD)in uplink non-orthogonal multiple access(NOMA)systems,including single-carrier and multi-carrier cases.In particular,we first propose a novel algorithm to estimate the active users and the channels for single-carrier based on complex alternating direction method of multipliers(ADMM),where fast decaying feature of non-zero components in sparse signal is considered.More importantly,the reliable estimated information is used for AUD,and the unreliable information will be further handled based on estimated symbol energy and total accurate or approximate number of active users.Then,the proposed algorithm for AUD in single-carrier model can be extended to multi-carrier case by exploiting the block sparse structure.Besides,we propose a low complexity MUD detection algorithm based on alternating minimization to estimate the active users’data,which avoids the Hessian matrix inverse.The convergence and the complexity of proposed algorithms are analyzed and discussed finally.Simulation results show that the proposed algorithms have better performance in terms of AUD,CE and MUD.Moreover,we can detect active users perfectly for multi-carrier NOMA system.

Capillary Electrophoretic Determination of Jinggangmycin A in Formulations Using Direct UV Detection

A simple, fast and reliable method was developed for the analysis of jinggangmycin A （validamycin A） in commercial formulations. The running buffer used was acetate buffer （100 mmol/L, pH 4.7） with 15 kV as the applied voltage. The detection was achieved by using direct UV mode at 200 nm and the detection limit was 0.2 μg/mL. Linearity in the concentration range of 5-500 μg/mL was excellent （RE 〉 0.999）. The run-to-run repeatability （n = 3）, as expressed by the relative standard deviation （RSD） for migration times and peak areas were less than 0.5% and 3.0% respectively. The mean recovery ranged from 97.2% to 101.4%.

Direct detection of rpoB and katG gene mutations of Mycobacterium tuberculosis in clinical samples

To study the rpoB and katG gene mutation rate and its markers.MethodsCross-sectional study methods were used to study Tuberculosis. A total of 45 sputum samples were collected from Annapurna Neurological Institute and Allied sciences. Then, acid fast bacilli staining were performed. Positive and negative samples were carried for conventional polymerase chain reaction identification and electrophoresis.ResultsOut of 45 samples, 3 were acid fast bacilli positive and the rest were negative. Male participants were more as compare to female participants and the mutation in rpoB and katG gene was found similar i.e. 6.66% among the total samples.ConclusionsWe can conclude that genetic mutation in Mycobacterium tuberculosis can be identified directly from the clinical samples. However, we have carried this study in less sample size and to validate research on large number of sample is recommended.

Detection of Target Genes in Viable Bacteria and Extracellular DNA Using Loop-Mediated Isothermal Amplification Assay

When the loop-mediated isothermal amplification(LAMP)assay is used for detecting target genes,DNA extraction is unnecessary in many cases.Simple pretreatment(e.g.heating)is enough to obtain rather sensitive responses.Even test samples without any pretreatment can be used as template.This feature suggests that LAMP is superior to PCR in developing point-of-care test strategies.In this study,using Stx1 gene from E.coli as model,we verified that viable cells,dead cells and extracellular DNA could function as template in the LAMP assay.In the incubation at 63℃,viable bacteria in the LAMP reaction mixture lysed completely within 2 min,providing DNA template for nucleic acid amplification.The Stx1 gene in diluted culture medium,spiked tap water,spiked seawater and real seawater all could be detected,with or without the step of DNA extraction.We found that the complex substances in real sample(e.g.natural seawater)exhibited considerable inhibitory effect on the sensitivity of the LAMP assay.These outcomes are meaningful for building a point-of-care strategy by employing the LAMP assay for environmental monitoring,bio-resource surveys,food safety,etc.in particular those based on environmental DNA.

Greater than 200 Gb/s Transmission Using Direct-Detection Optical OFDM Superchannel

In this paper, we propose directdetection optical orthogonal frequency division multiplexing superchannel （DDOOFDMS） and optical multiband receiving method （OMBR） to support a greater than 200 Gb/s data rate and longer distance for direct-detection systems. For the new OMBR, we discuss the optimum carriertosideband power ratio （CSPR） in the cases of backtoback and post transmission. We derive the analytical form for CSPR and theoretically verify it. A low overhead training method for estimating I/Q imbalance is also introduced in order to improve performance and maintain high system throughput. The experiment results show that these proposals enable an unprecedented data rate of 214 Gb/s （190 Gb/s without overhead） per wavelength over an unprecedented distance of 720 km SSMF in greater than 100 Gb/s DDOFDM systems.

Direction Detecting System of Indoor Smartphone Users Using BLE in IoT

Indoor organization user activity’s (UA) direction detection monitoring system and also emergency prediction are major challenging tasks in the field of the typical body sensor and indoor fixed sensor networks. In this paper, indoor UA based direction detection monitoring system is achieved by the combination of both the orientation sensor and Bluetooth Low Energy (BLE) in user’s smartphones belonging to the Internet of Things (IoT). The orientation sensor senses the actual orientation of the user and BLE transmits the sensed BLE signals to monitoring system using star topology in IoT. In monitoring system, classification algorithm is used to identify the directions of the smartphone users. The emergency situation of the user is also predicted based on signal variation instantly in real time. The user activity’s signals are captured using LabVIEW toolkit then applied to various classification algorithms such asRF—91.42%, Ibk—90.55%, j48— 85.61%, K*—73.54% are the results obtained. An average of 85% was obtained in all the classifi- cation algorithims indicating the consistency and accuracy in detecting the directions of the users. RF was found to be the best among all the classification algorithms. IoT enabled devices have high demand in near coming future, moreover smartphones users increase day by day, hence implementing and maintaining the above said system would be much easier and cheaper compared to other conventional networks.

Minimizing FWM Impact in DWDM ROF DP-DQPSK System for Optical

The demonstration of a higher data rate transmission system was amajor aspect to be considered by researchers in recent years. The most relevantaspect to be studied and analyzed is the need for a reliable system to handlenonlinear impairments and reduce them. Therefore, this paper examines theinfluence of Four-Wave Mixing (FWM) impairment on the proposed highdata rate Dual polarization–Differential Quadrature phase shift keying (DPDQPSK)system using the Optisystem software. In the beginning, the impactof varied input power on the proposed system’s performance was evaluated interms of QF and BER metrics. More power is used to improve system performance.However, increasing power would raise theFWMeffects. Accordingly,a−10dBminput power and the proposed system are used to reduce the impactof FWM. Additionally, a hybrid amplification method is proposed to enhancesystem performance by utilizing the major amplification methods of erbiumdopedfiber amplifier (EDFA): semiconductor optical amplifier (SOA) andRadio optical amplifier (ROA). The evaluation demonstrates that the OAEDFAoutperformed the other two key amplification techniques of (EDFASOA)and (EDFA-ROA) in improving Quality factor (QF) and Bit error rate(BER) system results for all distances up to 720 km. Consequently, the methodcontributes to minimizing the impact of FWM. In the future, other forms ofnonlinearity will be investigated and studied to quantify their impact on theproposed system.

Bidirectional intensity modulated/direct detection optical OFDM WDM-PON system

In this paper, we have evaluated a bidirectional wavelength division multiplexing passive optical network(WDM-PON) employing intensity modulated/direct detection optical orthogonal frequency division multiplexing(IM/DD-OFDM). The proposed system employs 100 Gbit/s 16 quadrature amplitude modulation(16-QAM) downstream and 5 Gbit/s on-off keying(OOK) upstream wavelengths, respectively. The proposed system is considered low-cost as non-coherent IM/DD OFDM technology and a simple reflective semiconductor optical amplifier(RSOA) colorless transmitter are employed and no dispersion compensating fiber(DCF) is needed. Based on the bit error rate(BER) results of WDM signals, the proposed WDM-PON system can achieve up to 1.6 Tbit/s(100 Gbit/s/λ × 16 wavelengths) downstream transmission over a 30 km single mode fiber(SMF).

Integrated Method of Recognizing Huge Target

An integrated novel method of recognizing huge target is described that combines some relatively mature image processing techniques such as edge detection, thresholding, morphology, image segmentation and so forth. After thresholding the edge image obtained by using Sobel operator, erosion is firstly used to reduce noise and extrusive pixels; then dilation is used to expand some separated pixels into various regions, after that the image segmentation technique is utilized to distinguish the target region with a criterion. The location of the target is also offered. Each technique adopted herein seems not complicated at all, the experimental results demonstrate the efficiency of the combination of these techniques. It is its high computational speed and remarkable robustness resulting from its simplicity that make the method promise to be applied in practical problems requiring real time processing.

Integrating cross-sensor high spatial resolution satellite images to detect subtle forest vegetation change in the Purple Mountains,a national scenic spot in Nanjing,China

Accurate information on the location and magnitude of vegetation change in scenic areas can guide the configuration of tourism facilities and the formulation of vegetation protection measures.High spatial resolution remote sensing images can be used to detect subtle vegetation changes.The major objective of this study was to map and quantify forest vegetation changes in a national scenic location,the Purple Mountains of Nanjing,China,using multi-temporal cross-sensor high spatial resolution satellite images to identify the main drivers of the vegetation changes and provide a reference for sustainable management.We used Quickbird images acquired in 2004,IKONOS images acquired in 2009,and WorldView2 images acquired in 2015.Four pixel-based direct change detection methods including the normalized difference vegetation index difference method,multi-index integrated change analysis(MIICA),principal component analysis,and spectral gradient difference analysis were compared in terms of their change detection performances.Subsequently,the best pixel-based detection method in conjunction with object-oriented image analysis was used to extract subtle forest vegetation changes.An accuracy assessment using the stratified random sampling points was conducted to evaluate the performance of the change detection results.The results showed that the MIICA method was the best pixel-based change detection method.And the object-oriented MIICA with an overall accuracy of 0.907 and a kappa coefficient of 0.846 was superior to the pixel-based MIICA.From 2004 to 2009,areas of vegetation gain mainly occurred around the periphery of the study area,while areas of vegetation loss were observed in the interior and along the boundary of the study area due to construction activities,which contributed to 79%of the total area of vegetation loss.During 2009–2015,the greening initiatives around the construction areas increased the forest vegetation coverage,accounting for 84%of the total area of vegetation gain.In spite of this,vegetation loss occurred in the interior of the Purple Mountains due to infrastructure development that caused conversion from vegetation to impervious areas.We recommend that:(1)a local multi-agency team inspect and assess law enforcement regarding natural resource utilization;and(2)strengthen environmental awareness education.

W-band radio-over-fiber transmission system with delta-sigma modulation and direct detection

We experimentally built a W-band photonics-aided millimeter-wave radio-over-fiber transmission system and demonstrated the delivery of up to 8192-ary quadrature amplitude modulation[QAM] signal.Discrete multitone signals are converted into 1-bit data streams through delta-sigma modulation and then modulated onto a 76.2 GHz carrier.An envelope detector is used at the receiver side for direct detection.The results prove that our proposed system can support 2048QAM and 8192QAM transmission while meeting the hard decision forward error correction threshold of 3.8×10^(-3)and the soft decision forward error correction threshold of 4.2×10^(-2),respectively.We believe this cost-effective scheme is a promising candidate for future high-order QAM millimeter-wave downlink transmission.

Cryo-ET bridges the gap between cell biology and structural biophysics

Cryo-electron tomography（cryo-ET） is a cutting-edge technology providing three-dimensional in situ ultra-structural information of macromolecular machineries, organelles, and eukaryotic cells in their native environment at an unprecedented level of detail. Cryo-ET enables the direct observation of dynamic macromolecular architectures of bio-samples in their naturally occurring physiological state, without any harmful artifacts introduced by heavy metal staining, dehydration, and chemical fixation, which occur in traditional transmission electron microscopy. Over decades, cryo-ET has been providing insights into numerous aspects of cellular biology by revealing the pristinely preserved ultra-structures of different cellular components comprising the crowded and complex environment of the cell, thus, bridging the gap between cellular biology and structural biophysics. In this paper, we review the fundamentals of this technique, its recent advances in optics, detection devices, and computational algorithms. The enhancement of our understanding of structural cellular biology by combining these improvements, when integrated with other methods, such as cryo-focused ion beam milling,correlative light and electron microscopy, is discussed via a few examples from research groups worldwide. We also believe that cryo-ET applications in cell biology continue to provide fundamental insights into the field, revolutionizing structural biology itself.

Beyond 100 Gb/s Optical OFDM Transmitted in Optical Long-Haul System

100 G Ethernet is considered to become the next generation Ethernet standard for IP networks.Typical 100 Gb/s transmission systems and their performance are presented.Comparision and analysis for 100 Gb/s transmission systems have been discussed.It is demonstrated that optical OFDM can be used in future 100 Gb/s/ch and long-haul system.

Dispersion Limit for IM/DD Fiberoptic Transmission Systems

A general formula for the dispersion limit of single-mode-fiber IM/DD (Intensity Modulation /Direct Detection) systems is derived for arbitrary given normalized pulse width P, eye opening penalty X and source linewidth enchancement factor α. From the comparison with published theoretical results, computer simulation and experimental data, its validity and convenience in system design and evaluation are shown. Using this simple and general formula, one can easily obtain the dispersion limit of various fiber types under different working conditions in IM/DD systems.

MLSE-assisted decision feedback equalizer for error-propagation suppression in high-speed IM-DD transmission systems

We propose a trellis-compressed maximum likelihood sequence estimation(TC-MLSE)-assisted sliding-block decision feedback equalizer(DFE)to suppress the error propagation resulting from the DFE in high-speed systems.We use an out-ofrange detector to detect the end of burst errors from the DFE and activate the optional TC-MLSE to correct burst errors.We conduct experiments to transmit a 201-Gbit/s PAM-8 signal.The results show that the proposed method achieves a bit error rate of 3.65×10^(-3),which is close to that of MLSE.The optional MLSE is only activated when needed and processes 11.4%of the total symbols.Moreover,the proposed method compresses the maximum length of burst errors from 19 to 5.

An improved bound on accelerated light dark matter

Light(sub-GeV)dark matter has gained increasing interest in terms of direct detection.Accelerated dark matter is a promising candidate that can generate detectable nuclear recoil energy within the sub-GeV range.Because of the large kinetic energy,its interactions with the nucleus are predominantly governed by inelastic scattering,including quasi-elastic and deep inelastic scattering.In this work,we calculated the inelastic effects in dark matter-Earth scattering mediated by a vector particle.Our analysis revealed that the impact of inelastic scattering relies on the mediator mass and the kinetic energy spectrum of dark matter.The results exhibited considerable disparity:the upper bounds of the exclusion limit for the spin-independent cross-section between accelerated dark matter and nuclei via a heavy mediator differ by several tens of times when inelastic scattering is considered.

Direct detection of the transient superresolution effect of nonlinear saturation absorption thin films

Using a strong nonlinear saturation absorption effect is one technique for breaking through the diffraction limit. In this technique, formation of a dynamic and reversible optical pinhole channel and transient superresolution is critical. In this work, a pump–probe transient detection and observation–experimental setup is constructed to explore the formation process directly. A Ge2Sb2Te5 thin film with strong nonlinear saturation absorption is investigated. The dynamic evolution of the optical pinhole channel is detected and imaged, and the transient superresolution spot is directly captured experimentally. Results verify that the superresolution effect originates from the generation of an optical pinhole channel and that the formation of the optical pinhole channel is dynamic and reversible. A good method is provided for direct detection and observation of the transient process of the superresolution effect of nonlinear thin films.

A novel modulation and direct detection scheme of optical phase shift keying

This paper introduces a new modulation and direct detection scheme of optical phase shift keying (PSK) which is simple and practical in fiber optical communication. A phase modulator is used to modulate a continuous wave (CW) laser source and return-to-zero (RZ) signal that is changed from the initial transmitting information is used to control a phase modulator to form a optical PSK signal. In the receiver terminal, just add a signal delayed a half of one bit to itself so that the initial information can be restored.

Have we found conclusive evidence for dark matter through direct detection experiments?

A WIMP-model-independent method is used to examine the existing evidence for low mass dark matter. Using XENON100＇s recent result of 224.6 live days × 34 kg exposure and PICASSO＇s result that was published in 2012, we have obtained constraints on the couplings │an│ 〈 0.4 and │ap│ 〈 0.3, corresponding to spin-dependent cross-sections of σ〈2.5×10^-38 cm2 and σp〈1.4×10^-38cm2 for a WIMP mass of 10 GeV/c2. It is shown that the spin-independent isospin-violating dark matter model also fails to reconcile the recent result from XENON100 with the positive results from DAMA, CoGeNT and CDMS-Ⅱ.

Progress review on the dark matter direct detection experiments

Subject Code:A05 A progress review article on the dark matter direct detection experiments,authored by Prof.Liu Jianglai(刘江来),Dr.Chen Xun(谌勋)and Prof.Ji Xiangdong(季向东,corresponding author)from the Shanghai Jiao Tong University,was published online in Nature Physics(2017,13:212—216)recently.