Using QuickBird imagery and a production efficiency model to improve crop yield estimation in the semi-arid hilly Loess Plateau,China

Crop yield is a key element in rural development and an indicator of national food security. A method that could estimate crop yield over large hilly areas would be highly desirable. Methods including high spatial resolution satellite imagery have the potential to achieve this objective. This paper describes a method of integrating QuickBird imagery with a production efficiency model (PEM) to estimate crop yield in Zhonglianchuan, a hilly area on Loess Plateau, China. In the PEM model, crop yield is a function of the photosynthetic active radiation (PAR), fraction of absorbed photosynthetically active radiation (f_APAR) and light-use efficiency (LUE). Based on the high spatial resolution QuickBird imagery, a land cover classification is used to attribute a class-specific LUE. The f_APAR is related to spectral vegetation indices (SVI), which can be derived from the satellite images. The LUE, f_APAR and incident PAR data were combined to estimate the crop yield. Farmer-reported crop yield data in 80 representative plots were used to validate the model output. The results indicated QuickBird imagery can improve the accuracy of predicted results relative to the Landsat TM image. The predicted yield approximated well with the data reported by the farmers (r² = 0.86; n = 80). The spatial distributions of crop yield derived here also offers valuable information to manage agricultural production and understand ecosystem functioning.     

A New Discriminant Principal Component Analysis Method with Partial Supervision

Principal component analysis (PCA) is one of the most widely used unsupervised dimensionality reduction methods in pattern recognition. It preserves the global covariance structure of data when labels of data are not available. However, in many practical applications, besides the large amount of unlabeled data, it is also possible to obtain partial supervision such as a few labeled data and pairwise constraints, which contain much more valuable information for discrimination than unlabeled data. Unfortunately, PCA cannot utilize that useful discriminant information effectively. On the other hand, traditional supervised dimensionality reduction methods such as linear discriminant analysis perform on only labeled data. When labeled data are insufficient, their performances will deteriorate. In this paper, we propose a novel discriminant PCA (DPCA) model to boost the discriminant power of PCA when both unlabeled and labeled data as well as pairwise constraints are available. The derived DPCA algorithm is efficient and has a closed form solution. Experimental results on several UCI and face data sets show that DPCA is superior to several established dimensionality reduction methods.     

CoBTx-Net: A model for business collaboration reliability verification

Collaborative business process can become unreliable when business partners collaborate in a peer- based fashion without central control. Therefore, reliability checking becomes an important issue that needs to be dealt with for any generic solution in managing business collaboration. In this paper, we propose a novel Choreographical Business Transaction Net (CoBTx-Net) to model collaborative business process and to manage the collaboration by individual participants. Furthermore three reliability properties named Time-embedded dead marking freeness, Inter-organizational dead marking freeness, and Collaborative soundness are defined based on CoBTx-Net to verify (1) the violation of time constraint, (2) collaborative logic conflicts, and (3) the improper termination from individual organizations.

An Efficient Authentication Scheme for Access Control in Mobile Pay-TV Systems

In a mobile pay-TV system, a large number of messages are exchanged for mutual authentication purposes. In traditional authentication schemes, with one-to-one delivery, one authentication message per request is delivered from a head end system to subscribers. This results in the delivery of a large quantity of messages and therefore is inefficient and costly. Moreover, since most traditional schemes use an RSA-based signature for identity validation and nonrepudiation of communication, they suffer from high communication costs. Due to its wireless nature, mobile pay-TV is vulnerable to attacks during hand-off. As traditional schemes do not support hand-off authentication, they are insecure during hand-off. With these shortcomings, they are not suitable for mobile pay-TV. In this paper, we propose an innovative authentication scheme, in which, by providing one-to-many facility, only one authentication message for multiple requests is broadcasted from the head end system to subscribers. By employing bilinear property of pairing and elliptic curve cryptography, our scheme provides one-to-many facility in the case of multiple requests for the same service in a short period of time. This new scheme achieves better broadcast efficiency and performance on communication costs than traditional ones. Additionally, this scheme provides a hand-off authentication mechanism to protect the access of services while preventing attacks during hand-off; therefore, the scheme is more secure to support access control. Moreover, to provide anonymous authentication for protecting identity privacy, the scheme adopts an identity-based scheme while traditional schemes do not apply. The scheme inherits advantages of the identity-based scheme that a public key does not need to be certificated, the certification authority mechanism will not be needed and the key exchange overhead can be reduced. With these advantages of our scheme, it is well suited for mobile pay-TV system.     

Granular Rough Theory: A representation semantics oriented theory of roughness

The present work is an archival paper for a series of contributions proposed in last few years on building a theory of roughness over pure mereological relations among information granules. There are five major efforts taken in the present paper: (1) emphasizing on the representational semantics of theory of roughness: to approximately represent a class of entities characterized by some aspects in terms of entity collections described at other aspects; (2) defining a representation model Granular Representation Calculus (GrRC) to synthesize complex information systems from information granules; (3) establishing notion of Granular Rough Theory (GrRT) over information granules operated in terms of GrRC; (4) extending GrRC/GrRT to various computational environments such as multi-agent systems and ontological computing environments; (5) exploring pragmatic aspects of GrRC/GrRT in implementing prototypes with data model and object programming orientations, and proposing an Ontology-Driven Web Information System as a granular-rough computational Web intelligence framework over GrRC/GrRT.     

Impulsive controller design for singular networked control systems with packet dropouts

This paper considers the problem of impulsive time-delay control for singular networked impulsive control systems(SNICSs) and uncertain SNICSs both with network-induced delay and packet dropouts. The parameter uncertainty is assumed to be norm bounded. The problem to be addressed is the design of robust impulsive time-delay feedback controllers such that the exponential stability of the resulting closed-loop system is guaranteed for admissible uncertainties. By applying Lyapunov function theory and Halanay Lemma, impulsive time-delay controller is derived through solving LMIs. Numerical examples are provided to demonstrate the application of the proposed method.     

基于CAN总线的模态测试悬挂控制系统设计

阐述了模态测试悬挂控制系统的研究意义,分析了模态测试悬挂控制系统的工作原理和硬件结构,制定了适合模态试验悬挂控制系统的CAN通讯协议,设计了底层电磁力与气压控制软件、上/下位机通信软件和上层工控机监控软件;试验结果表明,基于CAN总线的模态测试悬挂控制系统具有控制精度高、工作稳定可靠、通信速度快和可扩展性强等特点,很好地实现了模态测试悬挂控制系统预期的研制指标。     

基础位移激励下椭圆抛物面碳纤维索网的振动

在考虑温度变化的基础上,研究椭圆平面双曲抛物面碳纤维索网在基础激励下的非线性振动问题,建立了椭圆平面双曲抛物面碳纤维索网在基础位移激励下的非线性振动方程,采用Galerkin原理及KBM法求得了椭圆平面双曲抛物面碳纤维索网非线性振动的近似解．在把碳纤维索网与钢丝索网比较的基础上,讨论分析了位移激励、温度、振幅、外阻尼等因素对椭圆平面双曲抛物面碳纤维索网非线性振动的影响,得到了碳纤维索网对温度变化不敏感,而钢丝索网受温度的影响却很大,且碳纤维索网振动特性优于钢丝索网振动特性的结论．     

基于B／S模式网络系统安全性研究与实现

文章给出了B／S模式下保证系统安全的主要实现方法。在系统设计以Struts结构为架构模式,结合J2EE技术,开发了网络教学管理与评估系统平台;该系统具有较强的网络安全性。文章给出了采用由容器提供的安全服务和由应用程序提供的安全服务共同设计实现的网络系统安全措施。同时探索了基于B／S模式的多种安全技术,研究了该类信息系统在安全性方面的特点。该网络教学管理与评估系统实际运行表明,文章给出的网络系统安全措施具有较强的推广应用价值。     

基于校园GIS环境的排课系统设计研究

结合学校实际情况和发展现状,提出基于校园GIS环境的排课系统设计方法,在传统的字符信息中融入空间地理信息,对排课问题中的各种约束条件进行分析,通过设定合理的排课原则和优先级,完成课程的编排,同时实现以校园GIS为基础的可视化的信息管理功能。