Research on Impulse Radio Ultra - wideband Positioning Method Based on Combined BP Neural Network and SVM

Intelligent tour guide is a comprehensive service based on tourist\u27s location, which is closely related to Geographic Information System (GIS), mobile positioning technology and Location-Based Service (LBS). But the intelligent tour guide field urgently needs the integrated positioning and navigation technology inside and outside the room. IR-UWB technology is suitable for positioning, tracking, navigation and communication in complex indoor environment, and is considered as the most potential indoor positioning technology to realize seamless connection between indoor and outdoor with outdoor positioning technologies such as GPS. However, one of the main problems facing IR-UWB positioning is Non-Line-Of-Sight (NLOS) error. Based on the advantages of BP neural network and support vector machine, this paper proposes a multi-model fusion algorithm to mitigate the NLOS propagation error of the time difference of arrival (TDOA) and the angle of arrival (AOA) of IR-UWB signal, and then uses TDOA/AOA hybrid positioning that mitigates the NLOS error. Simulation results show that the combined algorithm has stronger NLOS resistance and higher positioning accuracy than the single machine learning algorithm in mitigation NLOS errors

A prognostic estimation model based on mRNA-sequence data for patients with oligodendroglioma

BackgroundThe diagnosis of oligodendroglioma based on the latest World Health Organization Classification of Tumors of the Central Nervous System (WHO CNS 5) criteria requires the codeletion of chromosome arms 1p and 19q and isocitrate dehydrogenase gene (IDH) mutation (mut). Previously identified prognostic indicators may not be completely suitable for patients with oligodendroglioma based on the new diagnostic criteria. To find potential prognostic indicators for oligodendroglioma, we analyzed the expression of mRNAs of oligodendrogliomas in Chinese Glioma Genome Atlas (CGGA).MethodsWe collected 165 CGGA oligodendroglioma mRNA-sequence datasets and divided them into two cohorts. Patients in the two cohorts were further classified into long-survival and short-survival subgroups. The most predictive mRNAs were filtered out of differentially expressed mRNAs (DE mRNAs) between long-survival and short-survival patients in the training cohort by least absolute shrinkage and selection operator (LASSO), and risk scores of patients were calculated. Univariate and multivariate analyses were performed to screen factors associated with survival and establish the prognostic model. qRT-PCR was used to validate the expression differences of mRNAs.ResultsA total of 88 DE mRNAs were identified between the long-survival and the short-survival groups in the training cohort. Seven RNAs were selected to calculate risk scores. Univariate analysis showed that risk level, age, and primary-or-recurrent status (PRS) type were statistically correlated with survival and were used as factors to establish a prognostic model for patients with oligodendroglioma. The model showed an optimal predictive accuracy with a C-index of 0.912 (95% CI, 0.679–0.981) and harbored a good agreement between the predictions and observations in both training and validation cohorts.ConclusionWe established a prognostic model based on mRNA-sequence data for patients with oligodendroglioma. The predictive ability of this model was validated in a validation cohort, which demonstrated optimal accuracy. The 7 mRNAs included in the model would help predict the prognosis of patients and guide personalized treatment

The Influence of Subjective Socioeconomic Status on Life Satisfaction: The Chain Mediating Role of Social Equity and Social Trust

Life satisfaction is significantly influenced by social capital, a key sociological term that links people to their social surroundings. Through a survey of 17,217 Chinese residents, this study investigated the probable processes of how subjective socioeconomic status affects life satisfaction within the framework of social capital. The results indicate that there is a positive correlation between subjective socioeconomic status and life satisfaction. Subjective socioeconomic status influences citizens’ life satisfaction not only through the independent mediating effects of perceived social equity and social trust, but also through the chain mediation of perceived social equity and social trust. This research advances our knowledge of the mechanisms behind the association between subjective socioeconomic status and life satisfaction. In improving citizens’ life satisfaction, we should not only provide sufficient subjective socioeconomic status to improve it, but also focus on the improvement of their social equity perceptions and social trust

The application of Bounded Online Gradient Descent Algorithms for Kernel Based Online Learning in Tourist Number Forecasting

With the upgrade of tourism informationization and the rise of intelligent city construction, the Internet of Things, Cloud Computing and other information technologies have been widely used in the tourism industry, making the development model and technical framework of intelligent tourism become a hot issue. Aiming at the problems of insufficient preparation and inadequate reception capacity of scenic spots in recent years, this paper proposes to apply machine learning algorithm to predict the number of tourists, so as to make an early response. In this paper, the characteristics of the application of the number of tourists are analyzed. The fixed buffer kernel online gradient descent algorithm is used to predict the number of tourists, and the actual number of tourists is brought into the algorithm for experiments. Finally, the rationality of the experimental process and results is analyzed

Ballistic response and failure mechanisms of gradient structured Mg alloy

Due to their low density, high specific damping capacity and high shock absorbency, magnesium (Mg) alloys have great potential for development as high-performance lightweight armor materials in industrial applications. However, their applications are still limited owing to low strength, ductility and formability. Gradient structure design has been shown to be a good method for improving the mechanical properties and ballistic resistance of Mg alloy plate. This work aims to thoroughly reveal the root causes of ballistic performance enhancement of gradient structured (GS) Mg alloy armor material through ballistic tests and finite element simulations. Compared with homogeneous Mg alloy plate of the same dimensions, the impact energy absorption of GS plate is increased by about 40%. The enhanced strength and plasticity from the gradient structure design certainly contribute in part to the ballistic resistance. More importantly, the gradient structure results in a transition of failure modes from the typical petal-shaped dehiscence to delamination and shear fracture. Based on detailed finite element analysis, we deeply understand the deformation process and the effect of the gradient structure on the propagation of stress wave during ballistic impacting. The energy absorption by each defeat mechanism is also theoretically calculated to quantitatively interpret their intrinsic effects. Meanwhile, microstructural observations and fracture morphology have demonstrated the appearance of adiabatic shear bands along the boundary of the cylindrical plunger after ballistic perforation of GS plate. Therefore, the failure mode transition caused by gradient structure design must also play a major role in improving the ballistic resistance

Improvement of Scintillation Performance in Large Size Yttrium Doped BaF_2 Crystals

Barium fluoride (BaF_2) crystal with sub nanosecond scintillation has attracted a broad interest in the HEP community. One crucial issue is its slow scintillation component with 600 ns decay time, which causes pile-up. Our previous studies show that the slow component can be suppressed effectively by yttrium doping. In this work, a 160 mm long BaF_2 ingot with 5% yttrium doping was grown at BGRI, and was used to cut a 100 mm crystal and several small samples. Their optical and scintillation properties were measured at Caltech. The results confirm that yttrium doping effectively suppresses the slow component while maintaining its ultrafast light and light response uniformity unchanged. This is encouraging for a BaF_2 :Y crystal based ultrafast calorimeter for Mu2e-II

Development of Yttrium Doped BaF_2 Crystals for Future HEP Experiments

Because of their ultrafast scintillation with subnanosecond decay time, barium fluoride (BaF_2) crystals have attracted broad interest in the high energy physics and nuclear physics communities. One crucial issue, however, is its slow scintillation component with 600-ns decay time, which causes pile-up in a high rate environment. Previous studies show that the slow component can be suppressed effectively by rare earth doping. In this paper, we report investigations on a set of Φ 18 x 21 mm^3 BaF_2 cylinders doped with different yttrium levels grown at Beijing Glass Research Institute (BGRI), from which the optimized yttrium doping level was determined. A Φ 40 x 160 mm^3 BaF_2 ingot with 5 atomic % (at.%) yttrium doping was consequently grown at BGRI and was used to cut one 25 x 25 x100 mm^3 crystal and several thin slices. Their optical and scintillation properties were measured at Caltech. The results show that yttrium doping effectively suppresses the slow component while maintaining its ultrafast light unchanged. Research and development will continue to develop large-size BaF_2:Y crystals with improved optical quality for a fast BaF_2:Y crystal calorimeter for Mu2e-II

Enhanced thermoelectric performance of MnTe via Cu doping with optimized carrier concentration

Polycrystalline Mn1-xCuxTe (x = 0, 0.025, 0.05, 0.075) thermoelectric materials were prepared by a combined method of melt-quenching and hot press. The effect of Cu doping on the electrical resistivity, band gap, the Seebeck coefficient and thermal conductivity was investigated. The power factors of the Cu-doped samples increase greatly due to the decrease of electrical resistivity and the higher Seebeck coefficient in high temperatures. In addition, the thermal conductivities of the Cu-doped samples also reduce due to the extra phonon scattering from the point defects introduced by Cu doping. As a result, the thermoelectric performance of MnTe is greatly enhanced, and a maximum ZT value of ∼0.55 in the Mn0.925Cu0.075Te sample at 773 K is achieved, which is 35% greater than that of the pristine MnTe sample