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Search Results: 1 - 10 of 28350 matches for " Wenhao Zhu "
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Machine Learning Approaches to Predicting Company Bankruptcy  [PDF]
Wenhao Zhang
Journal of Financial Risk Management (JFRM) , 2017, DOI: 10.4236/jfrm.2017.64026
Abstract: Machine Learning has undergone a tremendous progress, which is evolutionary over the last decade. It is widely used to make predictions that lead to the most valuable decisions. Many experts in economics use models derived from Machine Learning as important assistance, and many companies would use Neural Network, a model in bankruptcy prediction, as their guide to prevent potential failure. However, although Neural Networks can process a tremendous amount of attribute factors, it results in overfitting frequently when more statistics is taken in. By using K-Nearest Neighbor and Random Forest, we can obtain better results from different perspectives. This paper testifies the optimal algorithm for bankruptcy calculation by comparing the results of the two methods.
Wireless Physical-Layer Identification: Modeling and Validation
Wenhao Wang,Zhi Sun,Ren Kui,Bocheng Zhu,Sixu Piao
Computer Science , 2015,
Abstract: The wireless physical-layer identification (WPLI) techniques utilize the unique features of the physical waveforms of wireless signals to identify and classify authorized devices. As the inherent physical layer features are difficult to forge, WPLI is deemed as a promising technique for wireless security solutions. However, as of today it still remains unclear whether existing WPLI techniques can be applied under real-world requirements and constraints. In this paper, through both theoretical modeling and experiment validation, the reliability and differentiability of WPLI techniques are rigorously evaluated, especially under the constraints of state-of-art wireless devices, real operation environments, as well as wireless protocols and regulations. Specifically, a theoretical model is first established to systematically describe the complete procedure of WPLI. More importantly, the proposed model is then implemented to thoroughly characterize various WPLI techniques that utilize the spectrum features coming from the non-linear RF-front-end, under the influences from different transmitters, receivers, and wireless channels. Subsequently, the limitations of existing WPLI techniques are revealed and evaluated in details using both the developed theoretical model and in-lab experiments. The real-world requirements and constraints are characterized along each step in WPLI, including i) the signal processing at the transmitter (device to be identified), ii) the various physical layer features that originate from circuits, antenna, and environments, iii) the signal propagation in various wireless channels, iv) the signal reception and processing at the receiver (the identifier), and v) the fingerprint extraction and classification at the receiver.
User Capacity of Wireless Physical-layer Identification: An Information-theoretic Perspective
Wenhao Wang,Zhi Sun,Ren Kui,Bocheng Zhu
Computer Science , 2015,
Abstract: Wireless Physical Layer Identification (WPLI) system aims at identifying or classifying authorized devices based on the unique Radio Frequency Fingerprints (RFFs) extracted from their radio frequency signals at the physical layer. Current works of WPLI focus on demonstrating system feasibility based on experimental error performance of WPLI with a fixed number of users. While an important question remains to be answered: within certain performance, what's the user number that WPLI can accommodate using different RFFs and receiving equipment. The user capacity of the WPLI can be a major concern for practical system designers and can also be a key metric to evaluate the classification performance of WPLI. In this work, we establish a theoretical understanding on user capacity of WPLI in an information-theoretic perspective. We apply information-theoretic modeling on RFF features of WPLI. An information-theoretic approach is consequently proposed based on mutual information between RFF and user identity to characterize the user capacity of WPLI. Based on this theoretical tool, the achievable user capacity of WPLI is characterized under practical constrains of off-the-shelf receiving devices. Field experiments on classification error performance are conducted for the validation of the information-theoretic user capacity characterization.
Anti-Tumor Effect and Mechanism of Parthenolide in Gastric Cancer Cellline BGC-823  [PDF]
Wenhao Zhu, Hanni Zhang, Yunliang Guo, Keli Ge, Yonghong Zhou
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105271
Objective: To study the anti-tumor effect and mechanism of parthenolide in gastric cancer cell BGC-823. Methods: The cck8 assay was used to detect the changes of BGC-823 cells viability after treatment with different con-centrations of parthenolide at different time points. The proliferation ability of BGC-823 cells was detected by clone formation assay. And the cell cycle and apoptosis were measured by flow cytometry. Meanwhile, to detect the different in intracellular ROS production levels, the fluorescence assay was used. And with the help of western blotting, cell cycle- and apoptosis-related protein expression can be detected. Results: Parthenolide could inhibit the viability of BGC-823 cells in a dose- and time-dependent manner (P < 0.01). In BGC-823 cells exposed to parthenolide, the apoptosis rate was found significantly increased (P < 0.01), and the protein expression of cleaved-caspase3, cleaved-caspase8, and cleaved-caspase9 significantly increased (P < 0.01); the cell cycle was arrested at G1phase (P < 0.01); the protein levels of CyclinD1 and CyclinE1 decreased (P < 0.01), and the expression of P53 and P21 protein increased (P < 0.01); massive intracellular ROS generation was found (P < 0.01). Furthermore, the nuclear protein levels of c-Myc, E2F1, and NF-κB and the protein level of phosphorylated STAT3 decreased in BGC-823 cells exposed to parthenolide (P < 0.01). Conclusion: Parthenolide may inhibit the proliferation of BGC-823 cells and induce G1-phase cell cycle arrest and apoptosis via inhibiting STAT3-c-Myc-E2F1 axis.
Visual Analysis of Real Estate Investment Trusts Research—A Bibliometric Analysis Based on CiteSpace III  [PDF]
Wenhao Meng, Kunchang Shen, Qiao An
American Journal of Industrial and Business Management (AJIBM) , 2015, DOI: 10.4236/ajibm.2015.512076
Abstract: As an income-based real estate asset securitization innovation born in 1960s, real estate investment trusts now have grown into the fourth important assets allocation choice behind stocks, bonds and cash in the US. With the status of REITs is rising in the investment decisions, the research literature about REITs is increasing either. In order to sort out this research literature effectively, this paper uses the visualization software CiteSpace to analyze the journal articles and references of REITs, which have been embodied by the web of science core collection. Also, this paper attempts to describe the development network and cooperation characteristics in REITs research field, at the same time, we expect this paper can provide ideas and evidence for academia to research REITs further.
ROS-Dependent Cell Death Induced by Parthenolide in Human Hepatoma Cell HepG2  [PDF]
Weihua Xu, Keli Ge, Yunliang Guo, Wenhao Zhu, Liping Liu, Yonghong Zhou
Open Access Library Journal (OALib Journal) , 2020, DOI: 10.4236/oalib.1106025
With the increase of the action time and dosing concentration, the proliferation of HepG2 cell was inhibited and its vitality gradually decreased. FCM showed that, with the increase of PN action time, the MMP gradually decreased; calcium ions flowed inwards; the cell cycle was arrested in phase G1; the cell apoptosis rate, especially late apoptosis and necrotic cells, increased. The shear expression of apoptosis-related proteins caspase3 and caspase9 was up-regulated; the shear expression of AIF, MIF and PARP1 proteins associated with Caspase-independent apoptosis, i.e. Parthanatos apoptosis, showed time-dependent up-regulation; the long and short expressions of anti-apoptosis protein FLIP showed different degrees of decrease; the ex-pression of autophagy-related proteins LC3A/B and becin-1 was up-regulated; the expression of P62 protein was down-regulated; the expression of cycle- related proteins P53, P27 and P21 increased significantly; the expression of CyclinD1 and CyclinE1 decreased. FCM was used to detect the increase of ROS with the action time of PN; and its generation level showed an increasing trend; after the combination with ROS scavenger NAC, there was no significant difference in cell viability with the control group. There was no significant difference in the expression level of relevant cell death protein with DMSO control group. There was no difference in intracellular ROS generation level with the control group. Conclusion: PN induces the ROS generation in HepG2 cell, blocks its cycle and causes apoptosis and au-tophagy to play an anti-tumor effect.
A Marshall-Olkin Power Log-normal Distribution and Its Applications to Survival Data
Wenhao Gui
International Journal of Statistics and Probability , 2013, DOI: 10.5539/ijsp.v2n1p63
Abstract: In this paper, using Marshall-Olkin transformation, a new class of Extended Power Log-normal distribution which includes the Power Log-normal and Log-normal distributions as special cases is introduced. Its characterization and statistical properties are studied. A real survival dataset is analyzed and the results show that the proposed model is flexible and appropriate.
Statistical Inferences and Applications of the Half Exponential Power Distribution
Wenhao Gui
Journal of Quality and Reliability Engineering , 2013, DOI: 10.1155/2013/219473
Abstract: We investigate the statistical inferences and applications of the half exponential power distribution for the first time. The proposed model defined on the nonnegative reals extends the half normal distribution and is more flexible. The characterizations and properties involving moments and some measures based on moments of this distribution are derived. The inference aspects using methods of moment and maximum likelihood are presented. We also study the performance of the estimators using the Monte Carlo simulation. Finally, we illustrate it with two real applications. 1. Introduction The well-known exponential power (EP) distribution or the generalized normal distribution has the following density function: where is the shape parameter. This family consists of a wide range of symmetric distributions and allows continuous variation from normality to nonnormality. It includes the normal distribution as the special case when and the Laplace distribution when . Nadarajah [1] provided a comprehensive treatment of its mathematical properties. Its tails can be more platykurtic ( ) or more leptokurtic ( ) than the normal distribution ( ). The distribution has been widely used in the Bayes analysis and robustness studies (see Box and Tiao [2], Genc [3], Goodman and Kotz [4], and Tiao and Lund [5].) On the other hand, since the most popular models used to describe the lifetime process are defined on nonnegative measurements, which motivate us to take a positive truncation in the model (1) and develop a half exponential power (HEP) distribution. As far as we know, this model has not been previously studied although, we believe, it plays an important role in data analysis. The resulting nonnegative half exponential power distribution generalizes the half normal (HN) distribution, and it is more flexible. In our work, we aim to investigate the statistical features of the nonnegative model and apply them to fit the lifetime data. The rest of this paper is organized as follows: in Section 2, we present the new distribution and study its properties. Section 3 discusses the inference, moments, and maximum likelihood estimation for the parameters. In Section 4, we discuss a useful technique, a half normal plot with a simulated envelope, to assess the model adequacy. Simulation studies are performed in Section 5. Section 6 gives two illustrative examples and reports the results. Section 7 concludes our work. 2. The Half Exponential Power Distribution 2.1. The Density and Hazard Function Definition 1. A random variable has a half exponential power slash distribution if
Singular rationally connected surfaces with non-zero pluri-forms
Wenhao Ou
Mathematics , 2013,
Abstract: This paper is concerned with projective rationally connected surfaces $X$ with canonical singularities and having non-zero pluri-forms, i.e. $(\Omega_X^1)^{[\otimes m]}$ has non-zero global sections for some m > 0, where $(\Omega_X^1)^{[\otimes m]}$ is the reflexive hull of $(\Omega_X^1)^{\otimes m}$. We show that any such surface can be obtained from a rational ruled surface by a very explicit sequence of blow-ups and blow-downs. Moreover, we interpret the existence of non-zero pluri-forms in terms of semistable reduction.
Lagrangian fibrations on symplectic fourfolds
Wenhao Ou
Mathematics , 2014,
Abstract: We prove that there are at most two possibilities for the base of a Lagrangian fibration from a complex projective irreducible symplectic fourfold.
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