Wyniki wyszukiwania - BazTech

1

Privacy preservation for transaction initiators: stronger key image ring signature and smart contract-based framework

Odoom Justice, Huang Xiaofang, Danso Samuel, Nyarko Benedicta Nana Esi

Computer Science

|

2023

|

T. 24 (1)

75--96

EN

Recently, blockchain technology has garnered a great deal of support; however, an attenuating factor to its global adoption in certain use cases is privacypreservation (owing to its inherent transparency). A widely explored cryptographic option to address this challenge has been a ring signature that, aside from its privacy guarantee, must be double-spending resistant. In this paper, we identify and prove a catastrophic flaw for double-spending attacks in a lightweight ring signature scheme and proceed to construct a new fortified commitment scheme that uses a signer’s entire private key. Subsequently, we compute a stronger key image to yield a double-spending-resistant signature scheme that is solidly backed by formal proof. Inherent in our solution is a novel, zero-knowledge-based, secure, and cost-effective smart contract for public key aggregation. We test our solution on a private blockchain as well as a Kovan testnet along with a performance analysis that attests to its efficiency and usability – and, we make the code publicly available on GitHub.

2

Lightweight Security Mechanism to Mitigate Active Attacks in a Mobile Ad-hoc Network

Ahamed Uthumansa, Fernando Shantha

International Journal of Electronics and Telecommunications

|

2022

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Vol. 68, No. 1

145--152

EN

Mobile Ad hoc Network (MANET) is a type of Ad hoc network. General properties of MANET open the network to various security threats. Network layer-based Active attacks are widespread and destructive. Available security solutions contain complex calculations. Therefore, the objective of this research is to propose a lightweight security mechanism to enhance the security of data communications between source and destination nodes in a MANET from network layer-based active attack. Blackhole is used as a network layer-based Active attack. The network performance is evaluated using Packet Delivery Ratio (PDR), Average End-to-End Delay (AEED), Throughput, and Simulation Processing Time at Intermediate Nodes (SPTIN). The controller network was used to compare the performance of each network. During the experiment due to the impact of the blackhole attack, compared to the controller network, the PDR was found to be 0.28%, AEED was infinity and Throughput was 0.33%. The performance of the proposed security mechanism was compared with that of the controller network, and the values of PDR, AEED, Throughput, and SPTIN were found to be 98.0825%, 100.9346%, 99.9988%, and 96.5660%, respectively. The data packet delivery ratio was 100.00% compared to that of the controller network. The network that was affected by a blackhole attack showed a higher amount of ADDR than the controller network and the lowest amount of PDR. The network that was affected by the blackhole showed underperformance compared to the controller network. The proposed security mechanism performs well in PDR, AEED, and Throughput compared to the controller network. The AEED and SPTIN values prove that the proposed solution is free from complex calculations. The scope of the solution can be expanded into a lightweight Intruder Detection System to handle different types of security attacks in MANETs.

3

A Review on the Performance and Comfort of Stab Protection Armor

Sitotaw Dereje Berihun, Ahrendt Dustin, Kyosev Yordan, Kabish Abera Kechi

Autex Research Journal

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2022

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Vol. 22, no. 1

96--107

EN

Stab-protective clothing is the most important component of safety equipment and it helps to save the lives of its wearers; therefore, it is designed to resist knife, nail, or needle attacks, especially to the upper body. In this paper, the essential requirements for stab-resistant armor are investigated based on an in-depth review of previous research and prototype test results. The combination of protection and comfort in armor vests is a particularly challenging task. Review of the state of the art technology responsible for the manufacture of stab-resistant clothes has revealed that their design and development should encompass the elements of comfort, freedom of movement, permeability, absorption, evaporation, and weight reductions to ensure excellent ergonomics and high wear comfort. The design as well as the production, weight, thickness, material types and properties, and the arrangement of scales determine the level of protection and comfort offered by stab-resistant vests. Currently, the production of stab-proof gear-based 3D printing technology is evaluated, using lightweight materials (aramid) in the form of segmented scales inspired by nature. As the protection performance and wear comfort of stab-proof gear is enhanced, the willingness of security, control, transport, custom, and correction officers to wear them can be significantly increased in an endeavor to ensure that fatal injuries will decrease significantly.

4

Simulation and optimization of a new energy vehicle power battery pack structure

Ruan Guanqiang, Yu Changqing, Hu Xing, Hua Jing

Journal of Theoretical and Applied Mechanics

|

2021

|

Vol. 59 nr 4

565--578

EN

With the rapid growth in new energy vehicle industry, more and more new energy vehicle battery packs catch fire or even explode due to the internal short circuit. Comparing with traditional vehicles, the new energy vehicles industry should pay more attention to safety of power battery pack structures. The battery pack is an important barrier to protect the internal batteries. A battery pack structure model is imported into ANSYS for structural optimization under sharp acceleration, sharp turn and sharp deceleration turn conditions on the bumpy road. Based on the simulation, the battery pack structure is improved, and suitable materials are determined. Then the collision resistance of the optimized battery pack is verified, and the safety level is greatly improved. While ensuring the safety and reliability of the battery pack structure, it also reduces the weight to satisfy the lightweight design and complies with relevant technical standards.

5

Bezpieczeństwo pożarowe w obiektach halowych na przykładzie lekkich konstrukcji z płyt warstwowych w okładzinach metalowych

Korycki Piotr Olgierd

Izolacje

|

2020

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R. 25, nr 9

62--64

PL

Przedmiotem artykułu jest bezpieczeństwo pożarowe w obiektach halowych na przykładzie lekkich konstrukcji z płyt warstwowych w okładzinach metalowych. Autor przedstawia specyfikę płyt warstwowych w kontekście bezpieczeństwa pożarowego budynków. Charakteryzuje klasy odporności pożarowej materiałów i obiektów budowlanych i przybliża klasyfikację badań ogniowych nad płytami warstwowymi oraz metodykę ich prowadzenia. Następnie przygląda się właściwościom ogniowym płyt warstwowych oraz odporności ogniowej ścian i przekryć dachowych budynku w zależności od klasy jego odporności pożarowej.

EN

The subject of the article is the fire safety in hall facilities on the example of lightweight structures made of sandwich panels in metal facing. The author presents the specificity of sandwich panels in the context of fire safety of buildings. He characterizes the classes of fire resistance of building materials and objects and brings closer the classification of fire tests on sandwich panels and the methodology of performing them. Then the Author looks at the fire properties of sandwich panels and the fire resistance of walls and roof coverings of the building depending on its fire resistance class.

6

Effect of Al/Cu Weight Fraction on the Mechanical and Electrical Properties of Al-Cu Conductors for Overhead Transmission Lines

Han Deokhyun, Kim Geon-Hong, Kim Jaesung, Ahn Byungmin

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1019--1022

EN

In the past few years, overhead copper transmission lines have been replaced by lightweight aluminum transmission lines to minimize the cost and prevent the sagging of heavier copper transmission lines. High strength aluminum alloys are used as the core of the overhead transmission lines because of the low strength of the conductor line. However, alloying copper with aluminum causes a reduction in electrical conductivity due to the solid solution of each component. Therefore, in this study, the authors attempt to study the effect of various Al/Cu ratios (9:1, 7:3, 5:5) to obtain a high strength Al-Cu alloy without a significant loss in its conductivity through powder metallurgy. Low-temperature extrusion of Al/Cu powder was done at 350ºC to minimize the alloying reactions. The as-extruded microstructure was analyzed and various phases (Cu9Al4, CuAl2) were determined. The tensile strength and electrical conductivity of different mixing ratios of Al and Cu powders were studied. The results suggest that the tensile strength of samples is improved considerably while the conductivity falls slightly but lies within the limits of applications.

7

The possibility of using waste materials in building materials

Nalewajko Marta

Ekonomia i Środowisko

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2019

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nr 4

123--135

EN

In recent years, great emphasis has been placed on the implementation of the principles of sustainable construction and environmental protection. Decreasing amount of natural resources and increasing amount of industrial waste have made it necessary to produce products with the use of recycled materials. A number of studies conducted allow us to state that artificial aggregates, industrial ashes and waste from the wood industry are widely used in the production of construction products. The aim of the article is to show that the use of waste materials will allow to reduce the weight and absorbability of concrete chips by using artificial aggregate type Certification and improve the thermal insulation of products through the use of sawdust and wood chips. A 2 factorial experience with a rotational experimental plan was planned. The article presents the results of physical and mechanical properties tests and statistical interpretation of the obtained results.

8

Experimental study on the shear strength of reinforced concrete beams cast with Lava lightweight aggregates

Nawaz W., Abdalla J. A., Hawileh R. A., Alajmani H. S., Abuzayed I. H., Ataya H., Mohamed H. A.

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 4

981--996

EN

This paper investigates experimentally the shear strength behavior of reinforced concrete (RC) beams cast with Lava lightweight aggregates as a replacement of normal coarse aggregates. A total of 24 shear deficient RC beams were fabricated and cast with normal (NWC) and lightweight (LWC) concrete and tested under three-point bending after 28 and 56 days. The variables of the experimental program include type of aggregate, concrete compressive strength, and beam size. The experimental results include load–deflection response curves along with failure mode for each beam specimen. The experimental result showed that all beams failed in a similar fashion, due to diagonal tension shear crack. However, a larger number of cracks with less spacing occurred in the LWC beams as compared to NWC specimens. Based on the experimental results, it can be also concluded that LWC specimens tested after 56 days achieved comparable shear strength results to that of NWC beams. In addition, the strength reduction factor (l) for LWC specimens was in the range of 0.69–0.98. The concrete shear strength (Vc) was also predicted using different shear design provisions and the results has shown that Eurocode 2 provisions yielded the lowest C. O.V. of 2.3 and 10.2% for NWC and LWC specimens, respectively.

9

Przegląd algorytmów kryptograficznych pod względem realizacji sprzętowego koprocesora do zastosowań mobilnych

Mazurkiewicz T., Rawski M.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

|

2016

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nr 11

1293--1298

PL

Dokonano przeglądu algorytmów kryptograficznych typu lightweight, uznawanych powszechnie za bezpieczne, a także ich oceny pod względem realizacji koprocesora kryptograficznego w strukturach programowalnych.

EN

In the paper an overview of lightweight cryptographic algorithms regarded as safe has been presented. Their evaluation in terms of cryptographic coprocessor implementation in programmable structures has been discussed.

10

Metal/Composite Hybrids for Lightweight Applications

Osiecki T., Nossol P., Czech A., Kroll L., Niesłony A., Łagoda T.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

2015

|

z. 106

73

EN

In fields of mechanical engineering, automotive and aircraft industry the increasing demands for efficient energy processes induce the development of load adjusted multi-material constructions. In particular – due to their higher stiffness, good impact behavior and high load capacity – hybrid structures made of fiber reinforced thermoplastics (FRP) and metals can provide a significant contribution for weight reduction and thus for saving natural resources. Compared to establish thermosetting systems like GLARE, ARALL and CARALL in aircraft the new hybrid material is predestined for automotive mass production because of the short cycle times by using thermoplastic polymers.

11

A study on superplastic forming of multiple sheet with integral stiffeners

Lee H.-S., Yoon J.-H., Yoo J.-T., Choi J.-U.

Inżynieria Materiałowa

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2014

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Vol. 35, nr 2

166--170

EN

Blow molding process is one of the common manufacturing processes in plastic and glass industry. The advantages include low cost of the tool and ability to mold complex part. In metallic system, a similar process like superplastic forming has been widely used in aerospace industry, since it is possible to fabricate very thin part and hence lightweight structure. The present study demonstrates superplastic blow forming process with IN718 and titanium and aerospace components with a complex shape which were successfully manufactured. These metals have been used for high temperature application like lightweight propulsion systems. It is interesting to notice high value of strain rate sensitivity obtained for titanium alloy, while this for IN718 was relatively low at the forming temperature. The result shows that the developed technology to design high temperature superplastic forming by the finite element method can be applied for nearly net shape forming 2-sheet, 3-sheet and 4-sheet stiffened panels for lightweight component of aerospace structure.

PL

Proces formowania przez nadmuchiwanie jest jednym z najpowszechniejszych procesów w przemyśle tworzyw sztucznych i szkła. Zalety tego procesu polegają na niskich kosztach narzędzi oraz zdolnościach do formowania złożonych części. W systemach metalicznych, podobny proces – formowanie nadplastyczne jest szeroko stosowane w przemyśle lotniczym, ponieważ umożliwia otrzymywanie bardzo cienkich grubości materiału a więc struktur lekkiej konstrukcji. Przedstawione studium demonstruje nadplastyczne formowanie przez nadmuchiwanie z wykorzystaniem IN178, tytanu oraz otrzymanie w ten sposób lotniczych komponentów o złożonym kształcie. Te metale są wykorzystane w aplikacjach wysokotemperaturowych takich jak lekkie systemy napędowe. Należy zwrócić uwagę na dużą wrażliwość na szybkość odkształcenia stopów tytanu, podczas gdy dla IN718 jest ona relatywnie niska w temperaturze formowania. Wyniki te pokazują, że rozwinięta technologia procesu projektowania wysokotemperaturowego formowania nadplastycznego za pomocą MES może być stosowana w postaci 2, 3, 4 arkuszowych paneli usztywniających dla lekkich komponentów przemysłu lotniczego.

12

Innovations in forming technologies

Kurka P., Schieck F.

Archives of Materials Science and Engineering

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2014

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Vol. 65, nr 2

72--76

EN

Purpose: of this paper is the research of implementation of lightweight materials (aluminium, magnesium) as an important contribution for significant weight savings. Design/methodology/approach: Higher process stability, improved material exploitations, and generall shortening of process chains are the most important aims of Fraunhofer IWU. The requirements of the future car ask for lightweight construction concepts, in which materials, design, and manufacturing processes harmonize optimally. Therefore, Fraunhofer IWU researches on forming and joining technologies in order to achieve the optimum usage of high-strength steels, aluminium, magnesium, and fiber composite materials. Findings: New forming technologies as press hardening or electromagnetic forming (EMF) bring positive effects by resource efficiency and energy savings. When developing new materials, it is important to design the whole process chain according to the specific material properties. Practical implications: Press hardening offers an effective method of forming high strength steels. EMF is a high-speed forming technology applicable for shaping, joining, and cutting electrically conductive sheet metal or hollow profile components. Originality/value: The usage of lightweight materials is only reasonable when their mechanical characteristics such as stability, stiffness, and temperature resistance are better than those of classic steel. The same is true for the material and production costs.

13

Development of a novel technology for rapidly rotating systems for medical technology

Klaeger U., Schmucker U., Galazky V.

Management and Production Engineering Review

|

2013

|

Vol. 4, No. 4

28--34

EN

Rapidly rotating systems such as centrifuges are widely used in medicine and laboratories to efficiently separate different constituents of liquids. Rotors, which hold sample containers, are an essential part of centrifuges. Since they are subjected to extreme mechanical loads, rotors are one of a centrifuge’s core safety components. Their deficits served as the point of departure for the development of a novel manufacturing technology, which is based on carbon fiber-reinforced polymers (CFRP). Its supporting structure is entirely in the loading plane, thus enabling the rotor to absorb higher centrifugal forces while requiring the same amount of material. The new design concept for the load-bearing structure includes a geodesically molded annular support member. It transmits forces better than present products and increases rigidity. In order to eliminate the known problems with obtaining the necessary manufacturing quality of hollow fiber composite bodies, the authors developed the process of centrifugal infusion. Their proposed solution is based on generating higher gravitation forces, thus effectively eliminating detrimental gas pockets and simultaneously optimizing surface quality and impregnation.

14

Simulation of branched biological structures for bionic inspired fibre-reinforced components

Hufenbach W. A., Gude M., Cichy F., Danczak M., Neinhuis Ch., Schwager H.

Kompozyty

|

2011

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R. 11, nr 4

304-309

EN

The load adapted design of complex lightweight bar frame works with nodes and branched profiles is a significant challenge from both the structural mechanical and the manufacturing point of view. The search for novel material efficient solutions increasingly leads to the use of fibre-reinforced composites as they exhibit good specific material properties and a high degree of design flexibility. In order to achieve an optimum design of thin-walled, branched, hollow composite structures, a bionic approach following the top-down principal is pursued and simulations of various Y- and T-shaped models are carried out. The typical characteristics of the ramification areas of selected plant structures are analysed using micro-mirror fringe projection and micro-computed tomography. The scientific findings of plant morphology gained by these analyses are transferred into FE-models for structural analyses and parameter studies. The anisotropy of fibre material, the morphological characteristics of the examined cacti and the technological restrictions of the braiding process are considered in the design process of simulation models. The results show a significant increase of stiffness of thin walled branched models with bioinspired design features compared to models constructed according to the state-of-the-art technologies.

PL

Bardzo duże wyzwanie, zarówno z perspektywy strukturalno-mechanicznej, jak również produkcyjnej stanowi projektowanie dostosowanych do obciążenia, złożonych, a zarazem lekkich konstukcji prętowych (ramowych) wraz z więzami i rozgałęzieniami z lekkich profili. Poszukiwanie wydajnych rozwiązań materiałowych prowadzi do wykorzystania materiałów kompozytowych wzmacnianych włóknami, gdyż oferują dobre właściwości materiałowe oraz dużą swobodę projektowania. W celu uzyskania optymalnej konstrukcji cienkościennych rozgałęzień kompozytowych zostały przeprowadzone symulacje numeryczne profili w kształcie litery T oraz Y z wykorzystaniem metody elementów skończonych. W pierwszej kolejności przeprowadzono optyczną digitalizację 3D charakterystycznych obszarów rozgałęzień wybranych roślin oraz analizę przy pomocy tomografii komputerowej. Na opracowanie modeli numerycznych z uwzględnieniem anizotropii zastosowanego materiału pozwoliły otrzymane wyniki analiz morfologii roślin, a także uwzględnienie specyfiki wykorzystanej metody wytwarzania, czyli wyplatania. Wyniki pierwszych symulacji pokazują znaczącą poprawę sztywności cienkościennych modeli rozgałęzień bazujących na konstrukcjach inspirowanych naturą w porównaniu z wynikami symulacji konstrukcji tradycyjnych.

15

Some remarks on the estimation of design characteristics of membrane LNG carrier

Chądzyński W.

Zeszyty Naukowe / Akademia Morska w Szczecinie

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2010

|

nr 21 (93)

34-39

EN

The statistical analysis of existing data of similar ships is an effective tool for an initial estimation of principal parameters of a ship to be designed. High values of the correlation coefficient could signify that a high level of geometric and weight similarity occurs. If this statement is proved and supported by other premises, it means that there is a possibility to create statistical relations allowing to estimate the parameters of ship being designed with a high level of accuracy. This paper presents such case concerning membrane LNG tankers. The resulting parametric relations could be used for the creation of coherent design variants useful for the process of multicriterial optimization of these ships.

PL

Statystyczna analiza danych o zbudowanych statkach podobnych jest skutecznym narzędziem dla wyznaczania pierwszego przybliżenia wymiarów głównych i innych parametrów budowanego statku. Wysoki stopień wzajemnej korelacji badanych parametrów statków podobnych może oznaczać, że statki te charakteryzują się bardzo dużym podobieństwem geometrycznym i ciężarowym. Jeśli ta teza zostanie udowodniona i poparta innymi przesłankami, to istnieje możliwość zbudowania zależności statystycznych, na podstawie których można wyznaczać parametry projektowanego statku z dużą dokładnością. Niniejsza praca przedstawia taki właśnie przypadek dotyczący membranowych gazowców LNG. Zbudowane na tej podstawie zależności parametryczne mogą być wykorzystane do generowania spójnych alternatyw projektowych w procesie wielokryteryjnej optymalizacji tych statków.

16

Effect of curing temperature on flexural properties of silica-based geopolymer-carbon reinforced composite

Tran D. H., Kroisová D., Louda P., Bortnovsky O., Bezucha P.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

|

Vol. 37, nr 2

492-497

EN

Purpose: The aim of this paper is to find out the curing temperature at which we can achieve the best mechanical properties and adhesion between silica-based geopolymer matrix (Q1) and carbon HTS 5631 1600tex 24K fibre. Design/methodology/approach: The carbon fibre was impregnated with silica-based geopolymer by means of home-made “impregnation machine”. This equipment was designed based on simulating the real pultrusion or filament winding technique. Composite samples were made manually in silicon mould and cured under hot vacuum bagging technique at different temperatures. Flexural properties were determined under three-point bending mode in accordance with British Standard BS EN ISO 14125:1998. The sections perpendicular to fibres and surfaces of the composites were analysed by means of scanning electron microscope (SEM) to estimate the adhesion between geopolymer matrices and fibre reinforcement. Findings: Relatively wide range of curing temperature from 70oC to 100oC at which we can obtain high flexural properties, maximal values of flexural strength 570 MPa, flexural modulus 65 GPa and relative deformation of composite was 0.98% when the composite was cured and dried at 75oC. Adhesion of the geopolymer matrix to carbon fibre was very good and hardly to determine the differences by SEM image observation within the range of optimal curing temperature. Research limitations/implications: The curing time was too long to provide the geopolymerization process before it had been completed, this factor caused that it should be carried out in the future and we may use liquid absorption to determine how many cavities are in the composites. Practical implications: The research presents original information on the influence of different curing temperatures on mechanical properties and micro-structure of silica-based geopolymer matrix – carbon composite. The results are useful for further investigations. Originality/value: Determining the optimal curing temperature and micro-structure of silica-based geopolymer system to make it easy to find the curing time and other conditions to get the best properties of this type of materials.

17

Stability and ultimate load of three-layered plates -- a parametric study

Grądzki R., Kowal-Michalska K.

Engineering Transactions

|

2003

|

Vol. 51, iss.4

445-459

EN

This work deals with the analysis of influence of some geometrical and material parameters of layers on the mass, critical stress and ultimate load of three-layered plates. The plates are built of metal outer layers and a composite core. To obtain the maximum load value, the analysis is carried out in the elasto-plastic range basing on the Tsai-Wu criterion and Prandtl-Reuss equations. The solution is obtained by an analytical-numerical method.

18

Beton komórkowy : ekonomiczny i zdrowy materiał do budowy domów

Łaś M., Zapotoczna-Sytek G.

Zeszyty Naukowe. Budownictwo i Inżynieria Środowiska / Akademia Techniczno-Rolnicza w Bydgoszczy

|

2001

|

Z. 32(235)

159-166

PL

W artykule przedstawiono właściwości techniczne i zalety ekonomiczne, które decydują o dużej skali stosowania betonu komórkowego w budownictwie. Ponadto omówiono walory zdrowotne i niewielki wpływ betonu na środowisko naturalne.

EN

The paper presents technical properties and economic advantages of AAC decisive on its large scope of application in construction. Moreover its healthy advantages and low environmental impact are also pointed out.