VirtFogSim: A parallel toolbox for dynamic energy-delay performance testing and optimization of 5G Mobile-Fog-Cloud virtualized platforms

It is expected that the pervasive deployment of multi-tier 5G-supported Mobile-Fog-Cloudtechnological computing platforms will constitute an effective means to support the real-time execution of future Internet applications by resource- and energy-limited mobile devices. Increasing interest in this emerging networking-computing technology demands the optimization and performance evaluation of several parts of the underlying infrastructures. However, field trials are challenging due to their operational costs, and in every case, the obtained results could be difficult to repeat and customize. These emergingMobile-Fog-Cloud ecosystems still lack, indeed, customizable software tools for the performance simulation of their computing-networking building blocks. Motivated by these considerations, in this contribution, we present VirtFogSim. It is aMATLAB-supported software toolbox that allows the dynamic joint optimization and tracking of the energy and delay performance of Mobile-Fog-Cloud systems for the execution of applications described by general Directed Application Graphs (DAGs). In a nutshell, the main peculiar features of the proposed VirtFogSim toolbox are that: (i) it allows the joint dynamic energy-aware optimization of the placement of the application tasks and the allocation of the needed computing-networking resources under hard constraints on acceptable overall execution times, (ii) it allows the repeatable and customizable simulation of the resulting energy-delay performance of the overall system; (iii) it allows the dynamic tracking of the performed resource allocation under time-varying operational environments, as those typically featuring mobile applications; (iv) it is equipped with a user-friendly Graphic User Interface (GUI) that supports a number of graphic formats for data rendering, and (v) itsMATLAB code is optimized for running atop multi-core parallel execution platforms. To check both the actual optimization and scalability capabilities of the VirtFogSim toolbox, a number of experimental setups featuring different use cases and operational environments are simulated, and their performances are compared

Learning to compress and search visual data in large-scale systems

The problem of high-dimensional and large-scale representation of visual data is addressed from an unsupervised learning perspective. The emphasis is put on discrete representations, where the description length can be measured in bits and hence the model capacity can be controlled. The algorithmic infrastructure is developed based on the synthesis and analysis prior models whose rate-distortion properties, as well as capacity vs. sample complexity trade-offs are carefully optimized. These models are then extended to multi-layers, namely the RRQ and the ML-STC frameworks, where the latter is further evolved as a powerful deep neural network architecture with fast and sample-efficient training and discrete representations. For the developed algorithms, three important applications are developed. First, the problem of large-scale similarity search in retrieval systems is addressed, where a double-stage solution is proposed leading to faster query times and shorter database storage. Second, the problem of learned image compression is targeted, where the proposed models can capture more redundancies from the training images than the conventional compression codecs. Finally, the proposed algorithms are used to solve ill-posed inverse problems. In particular, the problems of image denoising and compressive sensing are addressed with promising results.Comment: PhD thesis dissertatio

Performance evaluation of currently available VLSI implementations satisfying U-interface requirements for an ISDN in South Africa.

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering.This project report examines the performance of three VLSI U-interface implementations satisfying the requirements of Basic Access on an ISDN. The systems evaluated are the Intel 89120,Siemens PEB2090 and STC DSP144, operating on 2BIQ, MMS4J and SU32 line codes respectively. Before evaluating the three abovementioned systems, a review of the underlying principles of U-interface technology is presented. Included in the review are aspects of transmission line theory, line coding, echo-cancellation, decision feedback equalisation, and pulse density modulation. The functional specifications of the three systems are then presented followed by a practical evaluation of each system. As an aid to testing the transmission systems, an evaluation board has been designed and built. The latter provides the necessary functionality to correctly activate each system, as well as the appropriate interfacing requirements for the error-rate tester. The U-interface transmission systems are evaluated on a number of test-loops, comprising sections of cable varying in length and gauge. Additionally, impairments are injected into data-carrying cables, in order to test the performance of each system in the presence of noise. The results of each test are recorded and analysed. Finally, a recommendation is made in favour of the 2BIQ U-interface. It is shown to offer superior transmission performance, at the expense of a slightly higher transmit-power level.Andrew Chakane 201

Structural and functional properties of complexes involving G-quadruplex-based DNA aptamers

Despite significant advances in the prevention and treatment of thrombosis, this disease is still one of the leading causes of death worldwide. The anticoagulant drugs often used to control blood coagulation in many cases show adverse effects. Oligonucleotide aptamers have shown to be alternative specific anticoagulants, which are characterized by nonimmunogenicity and nontoxicity. Interestingly, a subclass of these aptamers that adopts a G-quadruplex-based structure is able to effectively modulate the activity and the generation of the human α-thrombin (thrombin). In particular, anti-thrombin aptamers that recognize either thrombin exosite I (TBA, NU172) or exosite II (HD22) were selected. Despite their excellent anticoagulant properties, new studies expand day-to-day in order to in-depth elucidate their mechanism of action and overcome some long-standing limitations, as the short circulating half-life in vivo. The research activity carried out in the frame of this PhD project has been focused on three intriguing aspects of the interaction between thrombin or its zymogen prothrombin and aptamers adopting a G-quadruplex or a mixed duplex/quadruplex structure. First, using a repertoire of different experimental and computational techniques, the impact that the binding of HD22_27mer aptamer at the exosite II has on the binding of TBA or NU172 at exosite I, and vice versa, was investigated. In particular, the crystal structure of the ternary complex formed by the thrombin with NU172 and HD22_27mer, extensive molecular dynamics simulations of different thrombin/aptamer complexes, and anticoagulant activity experiments were performed. Collectively, the findings provide a clear and detailed picture of the cooperative action that TBA or NU172 and HD22_27mer exert on thrombin inhibition. Secondly, structural studies on new analogues of thrombin binding aptamers were carried out. In particular, the crystal structures of the complexes between thrombin and three TBA variants, in which Thy3 contains functional substituents at N3 of the pyrimidine heterocycle, were solved. The results suggest an explanation for their higher binding affinity toward thrombin with respect to that of TBA. Moreover, a preliminary analysis of the crystal structures of the complexes between thrombin and two TBA variants, carrying modifications at 5ʹ and 3ʹ ends, was presented. Conversely, the structural and biochemical properties of NU172 variants incorporating hexitol nucleotides were investigated in solution, indicating the modification at the Thy9 as the most promising. Finally, a preliminary investigation of the interaction between prothrombin and some anti-thrombin aptamers recognizing exosite I was carried out. In particular, a thermodynamic analysis of the binding of TBA, RE31 and NU172 aptamers to thrombin and prothrombin was performed by means of ITC experiments. The results indicate the ability of the examined aptamers to recognize prothrombin pro-exosite I with an affinity similar to that shown for thrombin exosite I. Furthermore, the ability of prothrombin to act as molecular chaperone of aptamers was revealed by CD experiments. To increase the possibility to obtain crystallographic information on aptamer-prothrombin complexes, considering the high flexibility of the wild-type protein, the prethrombin-2 intermediate and two prothrombin mutants were recombinantly produced

HYDROTHERMAL CHEMISTRY, CRYSTAL STRUCTURES, AND SPECTROSCOPY OF NOVEL FLUORIDES AND BORATES

This dissertation is a two-part manuscript highlighting the utilities of the hydrothermal method for exploring phase space, then extending that to the targeted growth of potentially useful materials. Chapters 3 - 5 discuss the synthesis of Group 4 fluorides and oxyfluorides. The study of this class of compounds in regards to their single crystal structures is a rich, but neglected area. Among the Group 4 metals, compounds based on Zr and Ti have been extensively studied, while those based on Th and Hf are sparsely reported and those based on Ce(IV) are nearly completely neglected. Using the hydrothermal method, many new thorium, cerium(IV), and hafnium fluorides containing monovalent ions were synthesized and characterized. These systems exhibit great sensitivity toward both size and concentration of the monovalent metal in addition to experimental conditions such as temperature and reaction time. Interestingly, the descriptive and structural chemistries in the hafnium fluoride systems differ greatly from the thorium fluoride systems while showing no less structural variety. However, the structural chemistry in the cerium fluoride system acts as a bridge between thorium and hafnium fluoride systems. Crystal structures in these systems are introduced and discussed to describe the rich and varied chemistry. Several compounds exhibit luminescence from X-ray and UV-Vis excitations, and this interesting optical behavior is also discussed. Chapters 6 and 7 focus on using the hydrothermal method to grow crystals having other sorts of optical functionality. A particularly rich system in this sense is the rare earth (RE) borate system, which can be useful for nonlinear optical (NLO), lasing, and scintillator applications. In particular, YBO3 appears to be an especially versatile host, as it has an acentric crystal structure and can accommodate a wide range of rare earth dopants such as Nd(III), Er(III), and Yb(III), which can be used to generate lasing activity. Surprisingly, few single crystals of RE-doped YBO3 have been synthesized; in fact, recent work on RE-doped YBO3 powders has focused primarily on Eu(III). The absorption and emission spectra of the dopants in YBO3 show a definitive blue-shift of up to 10 nm as compared to the commonly-used laser hosts of yttrium aluminum garnet (YAG) and YVO4, and initial findings show comparable emissions to that of RE-doped YAG and YVO4. Another group of acentric borates, Na3(RE)9O3(BO3)8 (RE = Pr, Nd, Sm), were discovered in the process of synthesizing the RE-doped YBO3 compounds. Absorption/emission spectroscopy and lifetime measurements of these borates will also be discussed

Mixing multi-core CPUs and GPUs for scientific simulation software

Recent technological and economic developments have led to widespread availability of multi-core CPUs and specialist accelerator processors such as graphical processing units (GPUs). The accelerated computational performance possible from these devices can be very high for some applications paradigms. Software languages and systems such as NVIDIA's CUDA and Khronos consortium's open compute language (OpenCL) support a number of individual parallel application programming paradigms. To scale up the performance of some complex systems simulations, a hybrid of multi-core CPUs for coarse-grained parallelism and very many core GPUs for data parallelism is necessary. We describe our use of hybrid applica- tions using threading approaches and multi-core CPUs to control independent GPU devices. We present speed-up data and discuss multi-threading software issues for the applications level programmer and o er some suggested areas for language development and integration between coarse-grained and ne-grained multi-thread systems. We discuss results from three common simulation algorithmic areas including: partial di erential equations; graph cluster metric calculations and random number generation. We report on programming experiences and selected performance for these algorithms on: single and multiple GPUs; multi-core CPUs; a CellBE; and using OpenCL. We discuss programmer usability issues and the outlook and trends in multi-core programming for scienti c applications developers

Synthesis and Derivatisation of Hetero-Atomic Zintl Anions and Multi-Metallic Clusters of the Tetrel and Pentel Elements

Binary Zintl anions of the tetrel and pentel elements have been synthesized. The work's focus is on the synthesis and derivatization of Zintl anions and multi-metallic clusters of the elemental combinations of germanium/phosphorus and germanium/arsenic. Novel binary Zintl anions and multi-metallic clusters with the elements vanadium, niobium, tantalum, and cadmium are presented

Synchronization Techniques for Burst-Mode Continuous Phase Modulation

Synchronization is a critical operation in digital communication systems, which establishes and maintains an operational link between transmitter and the receiver. As the advancement of digital modulation and coding schemes continues, the synchronization task becomes more and more challenging since the new standards require high-throughput functionality at low signal-to-noise ratios (SNRs). In this work, we address feedforward synchronization of continuous phase modulations (CPMs) using data-aided (DA) methods, which are best suited for burst-mode communications. In our transmission model, a known training sequence is appended to the beginning of each burst, which is then affected by additive white Gaussian noise (AWGN), and unknown frequency, phase, and timing offsets. Based on our transmission model, we derive the Cramer-Rao bound (CRB) for DA joint estimation of synchronization parameters. Using the CRB expressions, the optimum training sequence for CPM signals is proposed. It is shown that the proposed sequence minimizes the CRB for all three synchronization parameters asymptotically, and can be applied to the entire CPM family. We take advantage of the simple structure of the optimized training sequence in order to design a practical synchronization algorithm based on the maximum likelihood (ML) principles. The proposed DA algorithm jointly estimates frequency offset, carrier phase and symbol timing in a feedforward manner. The frequency offset estimate is first found by means of maximizing a one dimensional function. It is then followed by symbol timing and carrier phase estimation, which are carried out using simple closed-form expressions. We show that the proposed algorithm attains the theoretical CRBs for all synchronization parameters for moderate training sequence lengths and all SNR regions. Moreover, a frame synchronization algorithm is developed, which detects the training sequence boundaries in burst-mode CPM signals. The proposed training sequence and synchronization algorithm are extended to shaped-offset quadrature phase-shift keying (SOQPSK) modulation, which is considered for next generation aeronautical telemetry systems. Here, it is shown that the optimized training sequence outperforms the one that is defined in the draft telemetry standard as long as estimation error variances are considered. The overall bit error rate (BER) plots suggest that the optimized preamble with a shorter length can be utilized such that the performance loss is less than 0.5 dB of an ideal synchronization scenario