Memory-Adjustable Navigation Piles with Applications to Sorting and Convex Hulls

We consider space-bounded computations on a random-access machine (RAM) where the input is given on a read-only random-access medium, the output is to be produced to a write-only sequential-access medium, and the available workspace allows random reads and writes but is of limited capacity. The length of the input is $N$ elements, the length of the output is limited by the computation, and the capacity of the workspace is $O(S)$ bits for some predetermined parameter $S$. We present a state-of-the-art priority queue---called an adjustable navigation pile---for this restricted RAM model. Under some reasonable assumptions, our priority queue supports $\mathit{minimum}$ and $\mathit{insert}$ in $O(1)$ worst-case time and $\mathit{extract}$ in $O(N/S + \lg{} S)$ worst-case time for any $S \geq \lg{} N$. We show how to use this data structure to sort $N$ elements and to compute the convex hull of $N$ points in the two-dimensional Euclidean space in $O(N^2/S + N \lg{} S)$ worst-case time for any $S \geq \lg{} N$. Following a known lower bound for the space-time product of any branching program for finding unique elements, both our sorting and convex-hull algorithms are optimal. The adjustable navigation pile has turned out to be useful when designing other space-efficient algorithms, and we expect that it will find its way to yet other applications.Comment: 21 page

Solar-Driven Multi-Effect Distillation Overview

Desalination technologies can be categorized into (i) nonmembrane-based technologies and (ii) membrane-based technologies, where among them, some technologies require thermal energy while others require electrical energy for operation. The multi-effect distillation (MED) technology is a nonmembrane-based technology mainly driven by thermal heat and a little amount of electricity to run the water pumps. The MED process mimics the natural water cycle, where freshwater is evaporated from seawater, leaving behind salts and other nonvolatile substances, and then the freshwater is collected and gets condensed. Similar to the natural water cycle, the MED process can be driven by solar energy. This article provides an overview of the solar-driven MED process, including its operation design and the appropriate integration with solar energy. In addition, the possibility of coupling a MED process with a concentrated solar power (CSP) plant for the cogeneration of clean electricity and freshwater is also discussed

Membrane Distillation Development for Concentrated Solar Thermal Systems

At present, both energy and water are predominantly supplied through the burning of fossil fuels. Going forward, new demand (and the replacement of retiring assets) is increasingly being met by sustainable technologies—largely driven by solar energy. This PhD thesis aimed to address two pressing Sustainable Development Goals, set out by the United Nations, ‘affordable and clean energy’ and ‘clean water’, by developing solar-driven desalination (D) technologies using two different approaches: ‘direct solar-desalination’ and ‘indirect solar-desalination’. The first approach used feedwater heated directly by a solar thermal collector for vacuum membrane distillation (VMD) for a small residential scale. In contrast, the second approach targeted the indirect use of energy from a concentrated solar power (CSP) plant via more well-established desalination processes for large-scale applications. In the first approach, this thesis successfully designed and manufactured the first hollow fiber-based multi-effect VMD that can internally recover the latent heat of the permeate vapor between effects using metallic hollow helical baffles, reducing the energy consumption by more than 60% and producing up to 20 L/h at less than 2 USD per cubic meter of freshwater. In the second approach, detailed numerical simulations found that replacing the power block’s condenser with a multi-effect distillation (MED) system can significantly improve the CSP plant’s payback period by 5% – 13% but at the expense of reducing the thermal efficiency by 7% – 11.5%. Another solution is to utilize some of the generated electricity from the CSP plant to operate reverse osmosis (either on-site or at a facility near the coast); however, this was found to hurt the plant’s revenue since some of the valuable electricity generated is consumed by the RO plant, instead of being sold to the grid. Another CSP-D solution is to replace the conventional steam Rankine cycle with a supercritical CO2 cycle, which can provide the necessary high-temperature waste heat to a MED process without any thermal efficiency reduction. Overall, this thesis examines the potential of utilizing the endless supply of solar energy to produce sustainable clean energy and freshwater that can ‘green-terraform’ arid lands and help water-stressed communities

Accuracy of high definition near infrared transillumination camera in detection of hidden proximal caries

Early caries detection became mandatory in modern dentistry. However, the traditional methods in caries detection had many limitations. Hence,a novel approach based on Near Infrared technology was introduced to overcome such limitations. Proximal surfac

Multi-Layer Hybrid Encryption: A Novel Approach for Enhanced V2X Security

In recent years, the pervasive integration of technology in various domains has opened up new avenues for cybersecurity threats and data breaches. The automotive industry, in particular, has experienced significant impacts from technological advancements, most notably with the advent ofvehicle-to-everything (V2X) communication. Ensuring a secure framework for data exchange among vehicles has emerged as a crucial concern in the realm of automotive cybersecurity.This manuscript presents a comprehensive examination of a novel hybrid-encryption-based secure data exchange system, accompanied by a proposed implementation for an automated emergency reporting system in the event of a car accident

An Innovative Word Encoding Method For Text Classification Using Convolutional Neural Network

Text classification plays a vital role today especially with the intensive use of social networking media. Recently, different architectures of convolutional neural networks have been used for text classification in which one-hot vector, and word embedding methods are commonly used. This paper presents a new language independent word encoding method for text classification. The proposed model converts raw text data to low-level feature dimension with minimal or no preprocessing steps by using a new approach called binary unique number of word "BUNOW". BUNOW allows each unique word to have an integer ID in a dictionary that is represented as a k-dimensional vector of its binary equivalent. The output vector of this encoding is fed into a convolutional neural network (CNN) model for classification. Moreover, the proposed model reduces the neural network parameters, allows faster computation with few network layers, where a word is atomic representation the document as in word level, and decrease memory consumption for character level representation. The provided CNN model is able to work with other languages or multi-lingual text without the need for any changes in the encoding method. The model outperforms the character level and very deep character level CNNs models in terms of accuracy, network parameters, and memory consumption; the results show total classification accuracy 91.99% and error 8.01% using AG's News dataset compared to the state of art methods that have total classification accuracy 91.45% and error 8.55%, in addition to the reduction in input feature vector and neural network parameters by 62% and 34%, respectively.Comment: Accepted @ 14th International Computer Engineering Conference (ICENCO2018), Faculty of Engineering , Cairo University, Egypt, Dec. 29-30, 201

Methyl 2-({6-[(1-meth­oxy-2-methyl-1-oxopropan-2-yl)carbamo­yl]pyridin-2-yl}formamido)-2-methyl­propano­ate

In the title compound, C17H23N3O6, the two meth­oxy­carbonyl C—O—C=O planes are inclined at dihedral angles of 5.3 (4) and 83.9 (4)° with respect to the central pyridine ring. An intra­molecular N—H⋯O hydrogen bond generates an S(5) ring motif. In the crystal, mol­ecules are linked into a chain along the c axis via C—H⋯O hydrogen bonds