Multidimensional vector radix FHT algorithms

In this paper, efficient multidimensional (M-D) vector radix (VR) decimation-in-frequency and decimation-in-time fast Hartley transform (FHT) algorithms are derived for computing the discrete Hartley transform (DHT) of any dimension using an appropriate index mapping and the Kronecker product. The proposed algorithms are more effective and highly suitable for hardware and software implementations compared to all existing M-D FHT algorithms that are derived for the computation of the DHT of any dimension. The butterflies of the proposed algorithms are based on simple closed-form expressions that allow easy implementations of these algorithms for any dimension. In addition, the proposed algorithms possess properties such as high regularity, simplicity and in-place computation that are highly desirable for software and hardware implementations, especially for the M-D applications. A close relationship between the M-D VR complex-valued fast Fourier transform algorithms and the proposed M-D VR FHT algorithms is established. This type of relationship is of great significance for software and hardware implementations of the algorithms, since it is shown that because of this relationship and the fact that the DHT is an alternative to the discrete Fourier transform (DFT) for real data, a single module with a little or no modification can be used to carry out the forward and inverse M-D DFTs for real- or complex-valued data and M-D DHTs. Thus, the same module (with a little or no modification) can be used to cover all domains of applications that involve the DFTs or DHTs.     

Inter-cell interference in multi-tier heterogeneous cellular networks: modeling and constraints

Telecommunication Systems - Interference is the main source of capacity limitation in wireless networks. In some medium access technologies in cellular networks, such as OFDMA, the allocation of...     

Modeling and Simulation for Transient Thermal Analyses Using a Voltage-in-Current Latency Insertion Method

This article presents a modeling and simulation method for transient thermal analyses of integrated circuits(ICs) using the original and voltage-in-current(VinC) latency insertion method(LIM). LIM-based algorithms are a set of fast transient simulation methods that solve electrical circuits in a leapfrog updating manner without relying on large matrix operations used in conventional Simulation Program with Integrated Circuit Emphasis(SPICE)-based methods which can significantly slow down the sol...     

A low-overhead and reliable switch architecture for Network-on-Chips

This paper proposes and evaluates Low-overhead, Reliable Switch (LRS) architecture to enhance the reliability of Network-on-Chips (NoCs). The proposed switch architecture exploits information and hardware redundancies to eliminate retransmission of faulty flits. The LRS architecture creates a redundant copy of each newly received flit and stores the redundant flit in a duplicated flit buffer that is associated with the incoming channel of the flit. Flit buffers in the LRS are equipped with information redundancy to detect probable bit flip errors. When an error is detected in a flit buffer, its duplicated buffer is used to recover the correct value of the flit. In this way, the propagation of the erroneous flits in NoC is prevented without any need to credit signals and, retransmission buffers. Using an HDL-based NoC simulator, the LRS is compared to two other widely used reliability enhancement methods: the Switch-to-Switch (S2S) and the End-to-End (E2E) methods. The simulation results show that the LRS consumes less power and provides higher performance compared to those of the E2E and S2S methods. More importantly, unlike the E2E and the S2S methods, the LRS has constant overheads, which makes it applicable in all working conditions. To validate the comparison, an analytical performance and reliability model is developed for the LRS, S2S and E2E methods. The results of the model match those obtained from the simulations while the proposed model is significantly faster.     

Characterization of vanadyl phthalocyanine based surface-type capacitive humidity sensors

This study presents the fabrication and characterization of novel surface-type capacitive humidity sensors using vanadyl phthalocyanine (VOPc) as the active material. The devices, which comprise three different thicknesses,have been fabricated using the thermal evaporation technique. A thin film of VOPc is deposited on thoroughly cleaned glass substrates with pre-pattemed Ag electrodes. The capacitive effect of the samples under humidity has been in-vestigated. Comparison of the samples with different thicknesses shows that the thinnest device seems more sensitive towards humidity. The humidity dependent capacitance properties of the sensor make it beneficial for use in commercial hygrometers.     

Engineering Iron Oxide Hollow Nanospheres to Enhance Antimicrobial Property: Understanding the Cytotoxic Origin in Organic Rich Environment

Engineered magnetic iron oxide nanoparticles with surprisingly high antimicrobial activity and excellent safety profiles to mammalian cell lines have been developed. Hematite hollow nanospheres (HNSs) are prepared by a facile hard templating method; reduction of hematite HNSs by H₂ leads to magnetite HNSs. The antimicrobial activity of magnetite HNSs towards Gram negative (Escherichia coli) and Gram positive (Staphylococcus epidermidis) bacteria is evaluated against hematite HNSs and conventional magnetite (C‐magnetite; diameter <50 nm). Superior antibacterial performance is observed for magnetite HNSs towards both E. coli and S. epidermidis over hematite HNSs and C‐magnetite. The origin of the antimicrobial activity of magnetite HNSs is the high leaching of iron ions in the presence of microorganisms, which leads to high generation of reactive oxygen species. Magnetite HNSs allow multiple‐fold increase in the generation of soluble iron ions over hematite HNSs and C‐magnetite, showing that control over both the composition and nanostructure is crucial to tune the antimicrobial activity of iron oxides. Based on the current findings, magnetic HNSs show promising potential antimicrobial applications.     

Prospects and challenges of using hydropower for electricity generation in Lebanon

In a region characterized by low water resources, Lebanon stands as an exceptional country in the Middle East. Several waterways present ample opportunity for utilization of hydropower. Before the civil war, several projects were undertaken to generate electricity through hydropower. A total installed capacity of 283 MW has aided Lebanon in supplementing its need of electricity from local renewable sources, thus reducing the overall bill of imported energy. The available hydropower generation constitutes currently 4–7% of the electricity generation depending on rainfall, with future plans expected to install another 205 MW of capacity. This use is in competition with water diversion for irrigation. Four different scenarios were analyzed to indicate the share of hydropower in the total production of electricity, with and without future irrigation and power projects, indicating that, by 2020, hydropower's share of electricity generation will vary between a maximum of 6.9% and a minimum of 1.2% depending on government plans regarding water use. Current value of potential energy available when water from the Litani river is used for hydropower is estimated to be around 20 cents per m³. Water uses planned should take this value into account.     

Second harmonic generation from LB superlattices containing two active components

Second harmonic generation has been observed from Langmuir-Blodgett multilayer arrays containing two active components. Both materials were based on long chain donor-acceptor dye compounds, but were designed with the donor-acceptor groups in opposite senses with respect to the hydrocarbon chain. Preliminary results indicate a significant enhancement of the second-order polarisability for this type of supermolecular array.     

Quantitative preparation of long chain thioethers from an oxo-trans-2-enoic ester and a 9,12-dioxo-trans-10-enoic acid

Branched-chain thioethers have been prepared from methyl 4-oxo-trans-2-hexadecenoate and 9,12-dioxo-trans-10-octadecenoic acid. The reagents involved in these preparations were mercaptoacetic and mercaptopropionic acids. The yields of these thioethers are almost quantitative.