17,399 research outputs found

    Waveform Design for 5G and Beyond

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    5G is envisioned to improve major key performance indicators (KPIs), such as peak data rate, spectral efficiency, power consumption, complexity, connection density, latency, and mobility. This chapter aims to provide a complete picture of the ongoing 5G waveform discussions and overviews the major candidates. It provides a brief description of the waveform and reveals the 5G use cases and waveform design requirements. The chapter presents the main features of cyclic prefix-orthogonal frequency-division multiplexing (CP-OFDM) that is deployed in 4G LTE systems. CP-OFDM is the baseline of the 5G waveform discussions since the performance of a new waveform is usually compared with it. The chapter examines the essential characteristics of the major waveform candidates along with the related advantages and disadvantages. It summarizes and compares the key features of different waveforms.Comment: 22 pages, 21 figures, 2 tables; accepted version (The URL for the final version: https://onlinelibrary.wiley.com/doi/abs/10.1002/9781119333142.ch2

    Optimization of injection molding parameter of ti-6al-4v powder mix with palm stearin and polyethylene for the highest green strength by using taguchi method

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    This paper present the Taguchi method of L27 (313) orthogonal array as a tool in optimization of Metal injection molding (MIM) parameters for the highest green strength. Injection pressure, injection temperature, powder loading, mold temperature, holding pressure and injection speed are Parameters to be optimized. Besides those, interaction of the injection pressure, injection temperature and powder loading were studied. The metal powder of Ti-6Al-4V is mixed with binder 60wt% of palm stearin and 40wt% of polyethylene successfully injected at optimum parameter condition: 350 bar of injection pressure, 140oc of injection temperature, 65vol% of powder loading, 50oc of mold temperature, 600 bar of holding pressure, and 10ccm/s of the injection rate. Analysis of variance (ANOVA) for the best signal to noise ratio (S/N) presents the contribution of the parameters to the quality characteristic (green strength). Results show that the mold temperature has highest significant percentage (27.59%) followed by powder loading (15.44%) and injection pressure (12.30%) Nevertheless, the analysis of variance does not show any contribution from interaction

    Corrosion study of pipeline material for seabed sediment in tropical climate

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    Corrosive environments such as marine sediments can cause corrosion to steel pipelines at any time when certain conditions are met. Seabed sediment could cause severe corrosion damage due to its corrosiveness to the pipelines buried under it. Many consequences could take place in case if there is incident in oil/gas pipelines. Successfully identifying elements of corrosion in marine sediment would enhance the future of steel structure protection and monitoring systems. This article focuses on the behaviour of corrosion rate of steel located near shore environment and the aim is to determine the effect of sediment on corrosion of steel. To investigate that, simulated near shore sediment conditions have been used where the steel coupons buried in sediments which have different characteristics. Weight loss technique has been implemented to determine the weight loss rate of the steel specimens. Based on the results of this study, metal weight loss increases as the duration of exposure to seabed sediment environment become longer. The sea sediment simulated condition has given significant levels of corrosion. Conclusively, the corrosion rate of steel in seabed sediment located in tropical region is complicated and further studies are suggested

    On the rate of convergence in periodic homogenization of scalar first-order ordinary differential equations

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    In this paper, we study the rate of convergence in periodic homogenization of scalar ordinary differential equations. We provide a quantitative error estimate between the solutions of a first-order ordinary differential equation with rapidly oscillating coefficients and the limiting homogenized solution. As an application of our result, we obtain an error estimate for the solution of some particular linear transport equations

    THE TECHNOLOGY OF MANUFACTURING FUEL FOR OIL LAMPS IN THE HELLENISTIC PERIOD: AN APPLIED STUDY THROUGH THE FINDINGS OF THE ALEXANDRIA NECROPOLIS PROJECT OF SHATBY, ALEXANDRIA [2020–2023]

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    تكنولوجيا صناعة وقود إضاءة المسارج بالعصر الهلينستي «دراسة تطبيقية من خلال مكتشفات مشروع جبانة الشاطبي بالإسكندرية 2020-2023 [Ar] يقدم هذا البحث دراسة تطبيقية وتجريبية لما تم الكشف عنه من بقايا مادة وقود الإضاءة التى كانت تستخدم للمسارج فى الفترة الهلّينستية، وكذلك دراسة بقايا لفتيل محترق عثر عليه ضمن مشروع ترميم وتطوير وحماية جبانة الشاطبى الأثرية، والذى نفذته جمعية الآثار بالإسكندرية بتمويل من مؤسسة أ.ج. لفنتيس القبرصية فى الفترة من 2020-2023م. تضمن المشروع إعادة استكشاف الجبانة الأثرية بإزالة الرديم المتراكم بها عبر الزمن. وجادت الجبانة بالعديد من القطع الأثرية تمثلت فى مسارج وأطباق فخارية وأوانى الحضرة وبقايا عظام بشرية. أثبتت التحاليل والفحوص أن الصخر الذى نحتت فيه الجبانة الأثرية أحد أنواع الحجر الجيرى، وأن المياه الجوفية الموجودة بالجبانة هى مياه تترواح نسبة المعادن الذائبة بها بين 1,7جم/لتر ودرجة أس هيدروجينى pH 7.1 . تم تحليل مادة الوقود بالتحليل الكروماتوجرافى الغازى المزود بمطياف الكتلة، حيث أثبت أن مادة الوقود ذات أصل بترولى. واستخدم الفحص بالميكروسكوب الإلكترونى الماسح لفحص بقايا عينة الفتيل المتفحم، وتبين أنها جزء من ساق نبات البوط، وتم تأكيد النتيجة بفحص التركيب التشريحى لساقى نباتى البردى والبوط كجانب تجريبى. [En] This paper is an applied and experimental study on the remains of the fuel material that was used in oil lamps in the Hellenistic period, as well as the remains of a burning fuel and oil lamp wick. These remains are among the finds of the project of restoration, development, and protection of the archaeological cemetery of Shatby, conducted by the archaeological Society of Alexandria (2020-2023), funded by the A.G. Leventis foundation, Cyprus. The entire cemetery of Shatby is hewn in the a type of limestone called Calcarenite, which is a sedimentary rock. The groundwater at the site is slightly alkaline (pH 7.1), with the total dissolved solids (TDS) at 1.7 g/L. Remains of lighting fuel were found during the removal of the accumulated rubble in the ancient cemetery, where they were analyzed using gas chromatography mass spectrometry (GC-MS) analysis which proved that they are composed of crude oil. Using a scanning electron microscope to examine the traces of wick ash, it appeared that the wick was made of the culm of Cyperus articulate. Based on experimental work, this was also proven by light microscopy examination of the culms of Cyperus articulate and Cyperus papyrus

    Effect of high-fat diet-induced obesity on thyroid gland structure in female rats and the possible ameliorating effect of metformin therapy

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    Background: Obesity is known to induce a state of lipotoxicity that affects the different organs of the body. Metformin is an antidiabetic drug commonly used in obesity treatment. It was known to improve thyroid function and its regulating hormones. Structural changes in the thyroid gland associated with obesity have not been well investigated. So, the aim of the present study is to detect structural changes in thyroid gland induced by obesity and to investigate the possible protective role of metformin therapy. Materials and methods: Thirty adult female albino rats were divided into three groups (10 rats each). Group I (control group), group II (rats fed with a high-fat diet), and group III (rats fed with a high-fat diet and treated with metformin therapy). After 12 weeks, rats from all groups were sacrificed. Blood samples were taken for measurement of lipid profile, thyroid stimulating hormone (TSH), free T3 and free T4. Thyroid glands were extracted and processed for histological and ultrastructural study. Morphometric measurements for the colloid area of thyroid follicles and height of the follicular cells were done. Results: Group I displayed normal biochemical parameters and architecture of the thyroid gland. Group II revealed disordered lipid profile, high TSH, free T3 and T4. Microscopically, large thyroid follicles with excessive colloid accumulation and decreased follicular cells height were seen. Some follicular cells showed pyknotic nuclei, vacuolated cytoplasm and disrupted basement membrane with mast cell infiltration of the thyroid tissue. Ultrastructurally, group II follicular cells showed loss of apical microvilli, dense shrunken nuclei, dilated endoplasmic reticulum, swollen damaged mitochondria with large intracellular vacuoles and colloid droplets. In group III, the biochemical parameters and structure of thyroid follicles were improved, and they had a near-normal appearance. Conclusions: Obesity induced by high-fat diet in female rats structurally and functionally changed the thyroid gland in a way that may explain hypothyroidism associated with obesity. These changes were improved by metformin therapy

    Mineral Content of Some Plant Foods Grown in Nigeria: A Review

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    Minerals are natural inorganic substances that possess definite chemical composition and atomic structure. Nearly five percent of the body is composed of inorganic materials, the minerals. Minerals do not serve as a source of energy for the body but have specific chemical functions. For this purpose, mineral content of some plant foods found in Nigeria were critically reviewed. The plant foods were classified into legumes (Vigna unguiculata, Cucurbitaceae, vigna subterranean, Arachis hypogeal, Glycine max, Phaseolus coccineus, Cajanus cajan, Kerstingiella geocarpa, Phaseolus vulgaris L., Phaseolus lunatus and Prosopis Africana); cereals (Zea mays, Sorghum bicolor, Pennisetum typhoides and Oryza sativa); roots and tubers (Dioscorea spp, Manihot esculanta, Xanthosoma sagititolium and Ipomoea batatas L.); fruits/vegetables/nuts (Musa spp, Psidium guajava, Carica papaya, Citrus sinensis, Ananus comosus, Malaudo mistica, Anarcardium occidentale, Veronia amygdalina L. and Dacryodes edulis). Atomic absorption spectrophotometric (AAS) method is used for the minerals determination except sodium and potassium which are usually determined using flame photometry while phosphorus is by using colorimetry. The mineral contents were found to be at the range of concentrations as Ca: 0.003 – 700.00, Mg: 0.0546 – 1420.10, Na: 0.0065 – 220.00, K: 0.010 – 817.40, P: 0.0130 – 5500.00 and Fe: 0.0067 – 36.00 mg/100g for legumes; Ca: 0.13 – 8490.00, Mg: 0.006 – 4571.00, Na: 0.019 – 375.69, K: 0.63 – 39856.00, P: 3.54 – 695.50 and Fe: 0.0005 – 1304.00 mg/100g for  fruits/vegetables/nuts; Ca: 1.05 – 290.00, Mg: 0.49 – 415.07, Na: 0.18 – 1365.05, K: 0.50 – 4276.04, P: 0.28 – 120.00 and Fe: 0.53 – 81.85 mg/100g for roots and tubers and Ca: 0.005 – 532.00, Mg: 1.54 – 348.30, Na: 0.006 – 520.00, K: 0.011 – 618.00, P: 73.00 – 46.30 mg/100g for cereals. Microelement concentrations of the foods varied appreciably. Zinc content was highest in Vigna unguiculata, Psidium guajava, Manihot esculanta and Zea mays with values of 162.00, 2209.00, 340.00 and 16.70 mg/100g, respectively. Legumes and fruits/vegetables/nuts are seen to be better sources of mineral than foods in the category of roots, tubers and cereals. Keywords: Legumes, cereals, fruits, vegetables, snuts, roots, tubers, minerals
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