استكشف المجموعة الواسعة من العناوين المتاحة.

Due to the ever-growing popularity mobile devices of various kinds have received worldwide, the demands on large-scale wireless network infrastructure development and enhancement have been rapidly swelling in recent years. A mobile device holder can get online at a wireless network access point, which covers a limited area. When the client leaves the access point, there will be a temporary disconnection until he/she enters the coverage of another access point. Even when the coverages of two neighboring access points overlap, there is still work to do to make the wireless connection smoothly continue. The action of one wireless network access point passing a client to another access point is referred to as the handover. During handover, for security concerns, the client and the new access point should perform mutual authentication before any Internet access service is practically gained/provided. If the handover protocol is inefficient, in some cases discontinued Internet service will happen. In 2013, Li et al. proposed a fast handover authentication mechanism for wireless mesh network (WMN) based on tickets. Unfortunately, Li et al.'s work came with some weaknesses. For one thing, some sensitive information such as the time and date of expiration is sent in plaintext, which increases security risks. For another, Li et al.'s protocol includes the use of high-quality tamper-proof devices (TPDs), and this unreasonably high equipment requirement limits its applicability. In this paper, we shall propose a new efficient handover authentication mechanism. The new mechanism offers a higher level of security on a more scalable ground with the client's privacy better preserved. The results of our performance analysis suggest that our new mechanism is superior to some similar mechanisms in terms of authentication delay.

Developing strategies for producing hydrogen economically and in greener ways is still an unaccomplished goal. Photoelectrochemical (PEC) water splitting using photoelectrodes under neutral electrolyte conditions provides possibly one of the greenest routes to produce hydrogen. Here, we demonstrate that chlorophyll extracts can be used as an efficient exfoliant to exfoliate bulk MoS2 and WS2 to form a thin layer of a MoS2/WS2 heterostructure. Thin films of solution-processed MoS2 and WS2 nanosheets display photocurrent densities of −1 and −5 mA/cm2, respectively, and hydrogen evolution under simulated solar irradiation. The exfoliated WS2 is significantly more efficient than the exfoliated MoS2; however, the MoS2/WS2 heterostructure results in a 2500% increase in photocurrent densities compared to the individual constituents and over 12 h of PEC durability under a neutral electrolyte. Surprisingly, in real seawater, the MoS2/WS2 heterostructure exhibits stable hydrogen production after solar illumination for 12 h. The synthesis method showed, for the first time, how the MoS2/WS2 heterostructure can be used to produce hydrogen effectively. Our findings highlight the prospects for this heterostructure, which could be coupled with various processes towards improving PEC efficiency and applications.

Three-party-authenticated key agreement allows two users to establish a common session key through a trusted server via an insecure communication channel. Early authenticated key agreement schemes were mostly based on either pairing operations, hash operations, or modular exponentiation operations. In 2011, Wang and Zhao took a new path and built their three-party-authenticated key agreement scheme on the basis of chaotic maps. By applying Chebyshev chaotic maps, Wang and Zhao succeeded in lifting their scheme up to a higher level of efficiency and security. In this paper, we shall propose a new three-party-authenticated key agreement scheme based on chaotic maps that can do without passwords. Keeping no password table, our new scheme is completely resistant to password guessing attacks. Besides that, our scheme also offers thorough privacy protection to the users, so the user forgery attack can cause no damage. Compared with the schemes currently available including Wang and Zhao’s work, our new scheme obviously provides better security.

In recent years, Radio Frequency Identification (RFID) applications of various kinds have been blooming. However, along with the stunning advancement have come all sorts of security and privacy issues, for RFID tags oftentimes store private data and so the permission to read a tag or any other kind of access needs to be carefully controlled. Therefore, of all the RFID-related researches released so far, a big portion focuses on the issue of authentication. There have been so many cases where the legal access to or control over a tag needs to be switched from one reader to another, which has encouraged the development of quite a number of different kinds of ownership transfer protocols. On the other hand, not only has the need for ownership transfer been increasing, but a part of it has also been evolving from individual ownership transfer into group ownership transfer. However, in spite of the growing need for practical group ownership transfer services, little research has been done to offer an answer to the need. In this paper, we shall present a new RFID time-bound group ownership delegate protocol based on homomorphic encryption and quadratic residues. In addition, in order to provide more comprehensive service, on top of mutual authentication and ownership delegation, we also offer options for the e -th time verification as well as the revocation of earlier delegation.

Vehicular Ad-Hoc Network (VANET) is an application of Ad-Hoc Network, which can significantly improve the efficiency of transportation systems. The authentication of information is particularly important in the VANET system, because of its significant impact, and the transportation systems may be paralyzed as a result of receiving the wrong traffic information. Hence, a lot of schemes have been proposed to verify the information of VANET. However, most of currently known schemes verify the information on a one by one basis. In real situation, the large amount of traffic flow will generate a lot of information at the same time. If the authentication method is authenticating one by one, it is bound to lead to information delays, and the system will have difficulty to achieve real-time performance. Therefore, we shall propose an improved authentication of the batch scheme based on bilinear pairing to make VANET more secure, efficient, and more suitable for practical use.

When doctors are fatigued, they often make diagnostic errors. Similarly, pharmacists may also make mistakes in dispensing medication. Therefore, object segmentation plays a vital role in many healthcare-related areas, such as symptom analysis in biomedical imaging and drug classification. However, many traditional deep-learning algorithms use a single view of an image for segmentation or classification. When the image is blurry or incomplete, these algorithms fail to segment the pathological area or the shape of the drugs accurately, which can then affect subsequent treatment plans. Consequently, we propose the Fuzzy DBNet, which combines the dual butterfly network and the fuzzy ASPP in a deep-learning network and processes images from both sides of an object simultaneously. Our experiments used multi-category pill and lung X-ray datasets for training. The average Dice coefficient of our proposed model reached 95.05% in multi-pill segmentation and 97.05% in lung segmentation. The results showed that our proposed model outperformed other state-of-the-art networks in both applications, demonstrating that our model can use multiple views of an image to obtain image segmentation or identification.

Nativism and Modernity is the first comparative study of xiangtu nativism in Taiwan and xungen nativism in China. It offers a new critical perspective on these two important literary and cultural movements in contemporary Chinese contexts and shows how nativism can be a vital form of place-based oppositional practice under global capitalism. While nativism has often been viewed in nostalgic terms, Ming-yan Lai instead focuses on the structural implications of nativist oppositional claims and their transformations of marginality into alternative discursive spaces and practices. Through contextual analysis and close readings of key texts, Lai addresses interdisciplinary issues of modernity and critically explores the two nativist discourses' various engagements with power relations covering a multitude of social differentiations, including nation, class, gender, and ethnicity.

Mobile Healthcare (m-Healthcare) systems, namely smartphone applications of pervasive computing that utilize wireless body sensor networks (BSNs), have recently been proposed to provide smartphone users with health monitoring services and received great attentions. An m-Healthcare system with flaws, however, may leak out the smartphone user’s personal information and cause security, privacy preservation, or user anonymity problems. In 2012, Lu et al. proposed a secure and privacy-preserving opportunistic computing (SPOC) framework for mobile-Healthcare emergency. The brilliant SPOC framework can opportunistically gather resources on the smartphone such as computing power and energy to process the computing-intensive personal health information (PHI) in case of an m-Healthcare emergency with minimal privacy disclosure. To balance between the hazard of PHI privacy disclosure and the necessity of PHI processing and transmission in m-Healthcare emergency, in their SPOC framework, Lu et al. introduced an efficient user-centric privacy access control system which they built on the basis of an attribute-based access control mechanism and a new privacy-preserving scalar product computation (PPSPC) technique. However, we found out that Lu et al.’s protocol still has some secure flaws such as user anonymity and mutual authentication. To fix those problems and further enhance the computation efficiency of Lu et al.’s protocol, in this article, the authors will present an improved mobile-Healthcare emergency system based on extended chaotic maps. The new system is capable of not only providing flawless user anonymity and mutual authentication but also reducing the computation cost.

Developing strategies for producing hydrogen economically and in greener ways is still an unaccomplished goal. Photoelectrochemical (PEC) water splitting using photoelectrodes under neutral electrolyte conditions provides possibly one of the greenest routes to produce hydrogen. Here, we demonstrate that chlorophyll extracts can be used as an efficient exfoliant to exfoliate bulk MoS and WS to form a thin layer of a MoS /WS heterostructure. Thin films of solution-processed MoS and WS nanosheets display photocurrent densities of -1 and -5 mA/cm , respectively, and hydrogen evolution under simulated solar irradiation. The exfoliated WS is significantly more efficient than the exfoliated MoS ; however, the MoS /WS heterostructure results in a 2500% increase in photocurrent densities compared to the individual constituents and over 12 h of PEC durability under a neutral electrolyte. Surprisingly, in real seawater, the MoS /WS heterostructure exhibits stable hydrogen production after solar illumination for 12 h. The synthesis method showed, for the first time, how the MoS /WS heterostructure can be used to produce hydrogen effectively. Our findings highlight the prospects for this heterostructure, which could be coupled with various processes towards improving PEC efficiency and applications.