Residual infrared absorption in as-grown and annealed crystals ofTi:Al2O3

Data for as-grown and partially oxidized samples of Ti:Al₂ O₃ grown by the vertical-gradient-freeze technique show that the residual infrared absorption in these samples is largely due to Ti³⁺-Ti⁴⁺ pairs. In agreement with this pair model, the residual absorption in as-grown samples has been substantially decreased by annealing in a reducing atmosphere. Data for an as-grown crystal grown by the heat exchanger method indicate the presence of a second mechanism for residual absorption that may set a lower limit on the ratio of this absorption to the Ti⁺³ absorption used to pump laser emission     

Oblivious access control policies for cloud based data sharing systems

Conventional procedures to ensure authorized data access by using access control policies are not suitable for cloud storage systems as these procedures can reveal valid access parameters to a cloud service provider. In this paper, we have proposed oblivious access control policy evaluation (O-ACE); a data sharing system, which obliviously evaluates access control policy on a cloud server and provisions access to the outsourced data. O-ACE reveals no useful information about the access control policy neither to the cloud service provider nor to the unauthorized users. Through the security analysis of O-ACE it has been observed that computational complexity to compromise privacy of the outsourced data is same as reverting asymmetric encryption without valid key pair. We have realized O-ACE for Google Cloud. Our evaluation results show the fact that O-ACE CPU utilization cost is 0.01–0.30 dollar per 1,000 requests.     

Energy efficient watchman based flooding algorithm for IoT-enabled underwater wireless sensor and actor networks

In the task of data routing in Internet of Things enabled volatile underwater environments, providing better transmission and maximizing network communication performance are always challenging. Many network issues such as void holes and network isolation occur because of long routing distances between nodes. Void holes usually occur around the sink because nodes die early due to the high energy consumed to forward packets sent and received from other nodes. These void holes are a major challenge for I-UWSANs and cause high end-to-end delay, data packet loss, and energy consumption. They also affect the data delivery ratio. Hence, this paper presents an energy efficient watchman based flooding algorithm to address void holes. First, the proposed technique is formally verified by the Z-Eves toolbox to ensure its validity and correctness. Second, simulation is used to evaluate the energy consumption, packet loss, packet delivery ratio, and throughput of the network. The results are compared with well-known algorithms like energy-aware scalable reliable and void-hole mitigation routing and angle based flooding. The extensive results show that the proposed algorithm performs better than the benchmark techniques.     

Structure-Based Low Complexity MMSE Channel Estimator for OFDM Wireless Systems

Wireless communication systems utilizing orthogonal frequency division multiplexing (OFDM) transmissions are capable of delivering high data rates over multipath frequency selective channels. This paper deals with joint estimation/interpolation of wireless channel using pilot symbols transmitted concurrently with the data. We propose a low complexity, spectrally efficient minimum mean square error channel estimator which exploits the correlation structure of channel frequency response for reducing the complexity. Specifically, it is shown that if pilots are inserted appropriately across OFDM subcarriers, the proposed algorithm requires no matrix inversion, thereby significantly relieving the computational burden without deteriorating the performance. Moreover, the knowledge of channel correlation is also not required for the proposed estimator. Simulation results validate that the proposed technique outperforms existing low-complexity variants in terms of mean square error and computational complexity.

     

Electrical conductivity of molybdenum phosphate (MoO3 : P2O5) glasses

The dc conductivity of molybdenum phosphate glasses with the batch composition [(MoO₃)_z(P₂O₅)_z-1 where z = 0.55, 0.60, 0.65, 0.70, and 0.75 has been studied. The non-linearity of the Arrhenius plot (ln() versus T^-1>) may be due to processes involving several similar activation energies, conduction by small polarons, or variable range hopping of carriers. The electrical conductivity results for these glasses have been discussed by applying the two models suggested by Meunier et al. and it has been found that the use of the small polaron model yields physically plausible values for W_H and W_D within experimental error.     

Microscopic and molecular evidence in support of rodent as a reservoir for dissemination of Leishmaniasis

Leishmaniasis is a worldwide public health problem and vector‐borne disease. It is caused by a diverse group of protozoan parasites that belong to the genus Leishmania and transmitted to humans through a bite of an infected female sand fly. Leishmaniasis has attained epidemic proportion in Khyber Pakhtunkhwa and raises serious concern over its management. The present research work was conducted in cutaneous leishmaniasis (CL) prevalent village named Surgul of district Kohat, Khyber Pakhtunkhwa with a focus to investigate whether rodent can act as a source for dissemination of leishmanial species or not. In this context, rodent samples were analyzed via morphological and molecular approaches to unveil prevalence of CL. It was reported that 12.5% of samples were positive for signs of leishmaniasis through microscopy and 18.75% through polymerase chain reaction (PCR). Supporting the findings further, the color character of rodents was also taken into consideration, which shows that light dark colored rodents were more infected (13.3%) compared to brown colored rodents (11.43%). Based on our findings, we speculate that small rodents are a possible reservoir of various leishmanial parasites and play a significant role in zoonosis and maintenance of their species.     

Producing efficient retrievability ranks of documents using normalized retrievability scoring function

In this paper, we perform a number of experiments with large scale queries to analyze the retrieval bias of standard retrieval models. These experiments analyze how far different retrieval models differ in terms of retrieval bias that they imposed on the collection. Along with the retrieval bias analysis, we also exploit a limitation of standard retrievability scoring function and propose a normalized retrievability scoring function. Results of retrieval bias experiments show us that when a collection contains highly skewed distribution, then the standard retrievability calculation function does not take into account the differences in vocabulary richness across documents of collection. In such case, documents having large vocabulary produce many more queries and such documents thus have theoretically large probability of retrievability via a much large number of queries. We thus propose a normalized retrievability scoring function that tries to mitigate this effect by normalizing the retrievability scores of documents relative to their total number of queries. This provides an unbiased representation of the retrieval bias that could occurred due to vocabulary differences between the documents of collection without automatically inflicting a penalty on the retrieval models that favor or disfavor long documents. Finally, in order to examine, which retrievability scoring function has better effectiveness than other for correctly producing the retrievability ranks of documents, we perform a comparison between the both functions on the basis of known-items search method. Experiments on known-items search show that normalized retrievability scoring function has better effectiveness than the standard retrievability scoring function.     

Security Requirement Management for Cloud-Assisted and Internet of Things—Enabled Smart City

The world is rapidly changing with the advance of information technology. The expansion of the Internet of Things (IoT) is a huge step in the development of the smart city. The IoT consists of connected devices that transfer information. The IoT architecture permits on-demand services to a public pool of resources. Cloud computing plays a vital role in developing IoT-enabled smart applications. The integration of cloud computing enhances the offering of distributed resources in the smart city. Improper management of security requirements of cloud-assisted IoT systems can bring about risks to availability, security, performance, confidentiality, and privacy. The key reason for cloud- and IoT-enabled smart city application failure is improper security practices at the early stages of development. This article proposes a framework to collect security requirements during the initial development phase of cloud-assisted IoT-enabled smart city applications. Its three-layered architecture includes privacy preserved stakeholder analysis (PPSA), security requirement modeling and validation (SRMV), and secure cloud-assistance (SCA). A case study highlights the applicability and effectiveness of the proposed framework. A hybrid survey enables the identification and evaluation of significant challenges.     

Controlling the Selectivity of Conjugated Microporous Polymer Membrane for Efficient Organic Solvent Nanofiltration

To realize selective separation of important small molecules in organic solvents with high permeability is highly desired but not attained yet, because it requires stringent control over selectivity in nanofiltration membranes. Here, a thiophene‐containing conjugated microporous polymer membrane, in which the pore size is finely tuned at the angstrom scale through postoxidation of the thiophene moieties, is reported. The successful modification is confirmed by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and water contact angle, leading to obvious pore size reduction evidenced by nitrogen adsorption. Upon postmodification, the selectivity of the membrane can be effectively controlled. In the pristine membrane, the methanol permeance reaches 32 liters per square meter per hour per bar (L m^?2 h^?1 bar^?1) with a molecular weight cut‐off (MWCO) of 800 g mol^?1. Significantly, after in situ postmodification of thiophene moieties, the largest pore size is reduced from 1.73 to 1.48 nm, giving rise to a remarkable decrease of MWCO from 800 to 500 g mol^?1, while the permeance of methanol still maintains as high as 21 L m^?2 h^?1 bar^?1.