Use Of Lattice Research Articles

Lattice use in rugby headguards

This project is related to the design of rugby headguards. The World Rugby regulations limit the ability of headguards to reduce impact force. As such, World Rugby approved headguards are not intended to reduce the risk of serious injuries, like concussion or skull fracture. Rather, current headguards only limit the risk of superficial injuries to the soft tissue, like lacerations and contusions. With concussions linked to CTE (Chronic traumatic encephalopathy), an improvement in headguards could lead to an increased quality of life for all rugby players. With about a quarter of all rugby union injuries being concussion in the 2021/2022 season, there is justification to explore new headguard designs with potential to reduce the risk of such injuries. With World Rugby and the RFL recently introducing new rules for tackle height to try to reduce concussion rates, headguards that offer more protection could also help to reduce concussion rates. A lattice is a structure made from connected cells. When used within protective devices, lattices have potential advantages over the materials traditionally used, such as foams, from reducing the overall mass to allowing forces to be spread more evenly throughout the structure. The aim of this study was to design and comparatively impact test a lattice against foam in relation to rugby headguards. Prior data was limited as most studies on lattices focused on combining materials to have either a hollow lattice or a filled lattice which is not applicable to this study due to World Rugby regulations on protective equipment which states no sandwich material. The FEA results show that the force is more equally distributed through the lattice then it is foam allowing a lower force to hit the base.

Analysis and comparison of the security of electronic signatures based on new quantum-resistant problems

Due to the development of quantum computers and quantum methods and algorithms, in order to ensure the security of information after the development of cryptographically relevant quantum computers, NIST conducted the NIST PQC competition. As a result of conducting three rounds of NIST PQC, NIST selected 4 candidates for standardization and four candidates for the fourth round (key encapsulation mechanisms BIKE, Classic McEliece, HQC, and SIKE (which the developers considered unreliable)). Due to the fact that selected algorithms are based on the use of lattices and to add diversity to this list through the use of general-purpose signatures, the process of standardizing additional digital signatures for quantum-resistant cryptography has been initiated.
 The following types of signatures are considered for the first round of this standardization process: code-based signatures, isogeny signatures, multivariate signatures, symmetric signatures, MPC-in-the-head, and NIST-defined "other" signatures. These "other" digital signatures are mostly based on new and promising post-quantum (quantum-resistant) problems.
 The purpose of the work is to analyze and compare candidates for quantum-resistant digital signatures, based on new and promising quantum-resistant problems, resistant to classical and quantum attacks and side-channel attacks. The paper provides comparison of four digital signatures classified by NIST as "other", namely: ALTEQ, eMLE-Sig 2.0, KAZ-SIGN, Xifrat1-Sign.I. For this purpose, the paper presents the basic principles of each of these digital signatures, their main parameters and available at the time of consideration attack vectors. The paper also provides unconditional criteria necessary for comparison. Digital signatures were compared according to such unconditional criteria as: possible lengths of the public key, possible lengths of the personal (secret) key, length of the result of cryptographic algorithm; and conclusions are made regarding the completeness of given comparison and the possibility of further research is highlighted.

An upper bound on the covering radius of the logarithmic lattice for cyclotomic number fields

Recently, in coding theory and cryptography, it has been important the diversified use of lattices. One use of them is to cover a space. Each lattice has a covering radius, a number corresponding to the radius of a ball whose translations by all the points of the lattice cover efficiently the space generated by a basis of it. A way to obtain lattices algebraically is from subgroups of the multiplicative group of units of a number field via the logarithm embedding. This includes the logarithm lattice. In this work, it is presented an upper bound on the covering radius of the logarithm lattice obtained from the units of general cyclotomic number fields via the logarithm embedding, which generalizes an upper bound present in a previous work for cyclotomic number fields of prime-power indices.

Unravelling the relation between Laser Powder Bed Fusion processing parameters and the mechanical behaviour of as built lattices in a novel Al–Cu–Mg–Ag–Ti–B alloy

Laser Powder Bed Fusion (L-PBF) allows manufacturing of lattice structures whilst enabling their integration within a complex shaped solid component to design locally different properties depending on the desired part functionality. The recently developed aluminium A205 alloy offers high strength, good corrosion resistance, thermal and electrical conductivity, hence is promising for such multifunctional components. However, knowledge on the mechanical performance of lattices is currently lacking specifically for A205, while knowledge on geometrical accuracy of lattices in general is limitedly available. Both limit the practical use of lattices. Therefore, this paper presents novel L-PBF work on as built rhombic dodecahedron A205 lattices with relative lattice densities (RD) 10%, 20% and 30% achieving high geometrical accuracy and with detailed investigations of microstructure, fatigue and quasi-static properties. This step is critical to move forward to multifunctional components. An in-depth L-PBF parameter optimisation identifies the significant difference between optimal parameters for lattices and bulk, hence the general importance of a dedicated optimisation for metal lattice structures. The results show a high and repeatable geometrical accuracy and relative material densities above 99% for RD 10% and 20%. For RD 30%, lack of fusion porosities were present without significantly affecting mechanical properties, indicating surface quality dominates the mechanical behaviour. In a final step, a modified local stress-based fatigue analysis was applied and discussed. The results indicate predictable and stable fatigue behaviour which allows reducing the amount of samples necessary to define a representative SN curve for each RD for other unit cells in the future.

Effective Mechanical Properties of AlSi7Mg Additively Manufactured Cubic Lattice Structures.

Lattice structures, whose manufacturing has been enabled by additive technologies, are gaining growing popularity in all the fields where lightweighting is imperative. Since the complexity of the lattice geometries stretches the technological boundaries even of additive processes, the manufactured structures can be significantly different from the nominal ones, in terms of expected dimensions but also of defects. Therefore, the successful use of lattices needs the combined optimization of their design, structural modeling, build orientation, and setup. The article reports the results of quasi-static compression tests performed on BCCxyz lattices manufactured in a AlSi7Mg alloy using additive manufacturing. The results are compared with numerical simulations using two different approaches. The findings show the influence of the relative density on stiffness, strength, and on the energy absorption properties of the lattice. The correlation with the technological feasibility points out credible improvements in the choice of a unit cell with fewer manufacturing issues, lower density, and possibly equal mechanical properties.

ESTETIKA EKSPRESI STRUKTUR DI TERMINAL PENUMPANG KAPAL LAUT

Structures in architecture acts as a load-bearing element on mechanical systems. In addition, structures can also provide spatial and aesthetic expressions in architectural with the use of certain techniques and materials that bring out the structure expression. The problem discuss in this paper relates to aesthetic parameters used to examine the structural expression on architectural. The research method used is descriptive analytical method conducted with study of the literature on aesthetics, based on parameters: visual complexity, texture and colour, symmetry of the form and familiarity using the case study of Ship Passenger Terminal building such as Qingdao Cruise Passanger Terminal, Kai Tak Cruise Terminal and Salerno Maritime Terminal.The result shows that visual complexity parameter were exposure the form of curved structures and folding structures, the use of lattice, single-mass, and different building imagery. The texture and colour parameter are subtle textures with curved patterns, use of aluminium or concrete materials,and ivory white to bring out the buildings with the color of the sea.The symmetry of the form parameter shows a natural scale, a rectangular geometric shape that is subjected to addition or subtraction, and the proportion 2:1 between the envelope and open façade. The familiarity parameter is repetition of asymmetric curved patterns form make rhythm that raises perception of the visual aesthetic of the building.

Innovative Approach to Evaluate the Mechanical Performance of Ti–6Al–4V Lattice Structures Produced by Electron Beam Melting Process

Additive manufacturing processes allow producing complex geometries which include structures with enhanced mechanical performance and biomimetic properties. Among these structures, the interests on the use of lattice are increasing for both medical and mechanical applications. The mechanical behaviour of the structure is closely correlated to its shape and dimension. However, up to now, far too little attention has been paid to this aspect. Hence, this work aims to explore the effect of geometry, dimension and relative density of the cell structure on the compressive strength of specimens with lattice structures. For this purpose, various Lattice structures are designed with different geometries and dimensions. This approach leads to having structures with different relativity densities. Replicas of the designed structure are produced using Ti–6Al–4V powder processed by electron beam melting process. The samples are tested under compression. A new approach to calculate the absorbed energy up to failure by the lattice structure is presented. The results show a close relationship between the mechanical performance of the structure and the investigated parameters. In contrast with the current literature, the presented experimental data and a collection of the literature data highlight that the lattice structures with similar relative density do not exhibit the same Young’s modulus values.

Post-Quantum Lattice-Based Cryptography Implementations

The advent of quantum computing threatens to break many classical cryptographic schemes, leading to innovations in public key cryptography that focus on post-quantum cryptography primitives and protocols resistant to quantum computing threats. Lattice-based cryptography is a promising post-quantum cryptography family, both in terms of foundational properties as well as in its application to both traditional and emerging security problems such as encryption, digital signature, key exchange, and homomorphic encryption. While such techniques provide guarantees, in theory, their realization on contemporary computing platforms requires careful design choices and tradeoffs to manage both the diversity of computing platforms (e.g., high-performance to resource constrained), as well as the agility for deployment in the face of emerging and changing standards. In this work, we survey trends in lattice-based cryptographic schemes, some recent fundamental proposals for the use of lattices in computer security, challenges for their implementation in software and hardware, and emerging needs for their adoption. The survey means to be informative about the math to allow the reader to focus on the mechanics of the computation ultimately needed for mapping schemes on existing hardware or synthesizing part or all of a scheme on special-purpose har dware.

Arithmetical Improvement of the Round-Off for Cryptosystems in High-Dimensional Lattices

With Lattice-based cryptography (LBC), ciphertexts are represented as points near a lattice, and Babai’s round-off algorithm allows to decrypt them when one knows the secret-key. Recently, an accelerated variant of the round-off, based on Residue Number Systems (RNSs), has been proposed. Herein, we combine this technique with the use of lattices of Optimal Hermite Normal Form (OHNF) and propose further refinements, so as to reduce the decryption complexity. This approach lends itself largely to data-level parallelism, allowing for low latency decryption operations on multi-core CPUs with Single Instruction Multiple Data (SIMD) extensions, and achieves high-throughput on GPUs. Finally, we are able to perform decryptions up to 20 times faster than the most efficient implementation in related art, which exploits the Mixed-Radix System (MRS), in an Intel i7 6700K CPU, and we are able to decrypt up to 11,832 messages/s in a Titan X GPU.

On the use of Lattice–Boltzmann method for simulating peristaltic flow of viscoplastic fluids in a closed cavity

In this work, we have numerically studied the effect of a fluid's yield stress on the single-species flow driven by large-amplitude peristaltic waves propagating with different phase shifts along the upper and/or lower walls of a closed cavity. A multiple-relaxation-time, Lattice Boltzmann code was developed for studying the effect of the Bingham number on the flow kinematics having assumed that the viscoplastic fluid of interest can be represented by the bi-viscous model. Numerical results show that the Bingham number has a strong effect on the flow kinematics with its severity being dependent on the parameters of the travelling wave. The Bingham number was also found to strongly affect the drift parameter―a measure of the mixing efficiency within the channel. It is concluded that, when dealing with the flow of viscoplastic fluids in a microchannel, it is better to go for large-amplitude asymmetric peristaltic waves if mixing enhancement is desired. For symmetric waves, it is possible for the drift parameter of Bingham fluids to be larger than that of Newtonian fluids provided that the wavenumber is sufficiently large and its amplitude is sufficiently small. And, when the amplitude ratio is small, it is better to work at small Womersley numbers in order to have a larger drift parameter.

SiGe Nanomembrane Quantum-Well Infrared Photodetectors

SiGe quantum wells are promising candidates for the development of intersubband light emitters and photodetectors operating at mid- and far-infrared wavelengths. By virtue of their inherent compatibility with the Si microelectronics platform, these devices may be integrated seamlessly within complex optoelectronic systems for sensing and imaging applications. However, the development of high-quality SiGe intersubband active layers is complicated by the large lattice mismatch between Si and Ge, which limits the number of quantum wells that can be grown on bulk Si substrates before the onset of structural degradation due to inelastic strain relaxation. To address this issue, we investigate the use of lattice matched growth templates consisting of quantum-well nanomembrane stacks that were at one point free-standing, allowing for the internal stress to be relaxed via elastic strain sharing rather than defect formation. SiGe quantum-well infrared photodetectors (QWIPs) based on this approach are developed and characterized. Efficient current extraction from these ultrathin devices is obtained by bonding the nanomembranes directly on a doped Si substrate. Pronounced photocurrent peaks at mid-infrared wavelengths are measured, with improved responsivity compared to otherwise identical devices grown simultaneously on the supporting Si substrate.

Lattices Over Eisenstein Integers for Compute-and-Forward

In this paper, we consider the use of lattice codes over Eisenstein integers for implementing a compute-and-forward protocol in wireless networks when channel state information is not available at the transmitter. We extend the compute-and-forward paradigm of Nazer and Gastpar to decoding Eisenstein integer combinations of transmitted messages at relays by proving the existence of a sequence of pairs of nested lattices over Eisenstein integers in which the coarse lattice is good for covering and the fine lattice can achieve the Poltyrev limit. Using this result, we show that both the outage performance and error-correcting performance of the nested lattice codebooks over Eisenstein integers surpass those of lattice codebooks over integers considered by Nazer and Gastpar with no additional computational complexity.

Effect Of Privacy On And Elements Of Identity In Muslim-Turkish Houses In Anatolia

“Culture” has a featured place among a large number of factors which are effective on the formation of house architecture. From time to time, it is observed that very different houses are formed in the same physical environment. Sometimes analogous houses can be seen under highly different environmental conditions. It is possible to mention the effects of different cultures and lifestyles on this.The study aims to reveal how the effect of privacy is reflected in spatial formation and architectural elements in Muslim-Turkish houses. The relationship of the Turkish House with the concepts of Ottoman, Anatolia, Muslim and tradition as well as coincidence and variations are addressed. The analytical and comparative method is employed in the study. The common elements in the architectural formation which are caused by the vital and cultural interactions in the Turkish houses in Anatolia and the Balkans are reflected in the form of analogies in the building facade character and in architectural elements. It is possible to gather the analogies in the Turkish houses not only in the context of Anatolia and the Balkans but also at different corners of Anatolia under the common ground of “culture”. The effects of culture are reflected in the house architecture in a wide range from the use of lattice in various spaces and elements to kapi saksaks besides the openings which vary on the building facades depending on location and story.In this study, the concept of Turkish House and the thorough investigations into this issue are considered and the effect of the factor of “privacy” on the formation of Muslim-Turkish houses in Anatolia is examined from different perspectives. The subject is presented via the examples of Turkish houses selected from various localities of Anatolia. How the inward character of the Turkish house and its understanding of privacy are reflected in the details of an architectural building besides its facade and spatial construct is conveyed via examples.The thorough investigation concerned is of importance to see how culture and lifestyle are reflected on architecture – in other words, to read culture from the formation of a house.

Microchip laser Q‐switched with GaInNAs/GaAs SESAM emitting 204 ps pulses at 1342 nm

A 1342 nm Nd:YVO4 microchip laser is reported, Q-switched with a dilute nitride GaInNAs/GaAs saturable absorber mirror. The laser produced optical pulses as short as 204 ps with 2.3 MHz repetition rate and 24 mW average output power. In comparison to conventional InP-based saturable absorber mirrors, the advantage of the proposed approach is the availability of excellent Bragg mirror materials that enable high reflectivity and more flexibility in designing the non-linear parameters owing to the use of lattice matched GaInNAs/GaAs quantum wells.

Effects of cross sections tables generation and optimization on rod ejection transient analyses

Best estimate analysis of rod ejection transients requires 3D kinetics core simulators. If they use cross sections libraries compiled in multidimensional tables, interpolation errors – originated when the core simulator computes the cross sections from the table values – are a source of uncertainty in k-effective calculations that should be accounted for. Those errors depend on the grid covering the domain of state variables and can be easily reduced, in contrast with other sources of uncertainties such as the ones due to nuclear data, by choosing an optimized grid distribution.The present paper assesses the impact of the grid structure on a PWR rod ejection transient analysis using the coupled neutron-kinetics/thermal-hydraulics COBAYA3/COBRA-TF system. For this purpose, the OECD/NEA PWR MOX/UO2 core transient benchmark has been chosen, as material compositions and geometries are available, allowing the use of lattice codes to generate libraries with different grid structures.Since a complete nodal cross-section library is also provided as part of the benchmark specifications, the effects of the library generation on transient behavior are also analyzed. Results showed large discrepancies when using the benchmark library and own-generated libraries when compared with benchmark participants’ solutions. The origin of the discrepancies was found to lie in the nodal cross sections provided in the benchmark.

Analyzing the Order Factor of Query Matrix in Private Information Retrieval Protocol for Outsourced Databases

In this paper, we present analysis of non-concurrent model of fast single-database Private Information Retrieval (PIR) scheme for maintaining data privacy with data confidentiality using encryption algorithm like AES for Outsourced Database Service (ODBS) Model. In this model encryption method maintains data confidentiality and a utility that help to create PIR reply which maintains data privacy. Single-database PIR schemes are generally unusable because of its expensiveness from computational point of view. This model suggests use of Graphics Processing Unit (GPU) commodity to process database. This model will help to achieve practical implementation of single-database PIR scheme which uses encryption algorithm to maintain data confidentiality as secondary goal and it serves to create database reply to maintain data privacy as primary goal. This paper shows some real time results that proves need of concurrency in PIR algorithms. Our paper describes the use of lattice based single-database PIR protocol with GPU as a processing unit to achieve high speed-up and hence, the performance of the system.

New horizons in sphere-packing theory, part II: lattice-based derivative-free optimization via global surrogates

Derivative-free algorithms are frequently required for the optimization of nonsmooth scalar functions in n dimensions resulting, for example, from physical experiments or from the statistical averaging of numerical simulations of chaotic systems such as turbulent flows. The core idea of all efficient algorithms for problems of this type is to keep function evaluations far apart until convergence is approached. Generalized pattern search (GPS) algorithms, a modern class of methods particularly well suited to such problems, accomplish this by coordinating the search with an underlying grid which is refined, and coarsened, as appropriate. One of the most efficient subclasses of GPS algorithms, known as the surrogate management framework (SMF; see Booker et al. in Struct Multidiscip Optim 17:1---13, 1999), alternates between an exploratory search over an interpolating function which summarizes the trends exhibited by existing function evaluations, and an exhaustive poll which checks the function on neighboring points to confirm or confute the local optimality of any given candidate minimum point (CMP) on the underlying grid. The original SMF algorithm implemented a GPS step on an underlying Cartesian grid, augmented with a Kriging-based surrogate search. Rather than using the n-dimensional Cartesian grid (the typical choice), the present work introduces for this purpose the use of lattices derived from n-dimensional sphere packings. As reviewed and analyzed extensively in Part I of this series (see Belitz, PhD dissertation, University of California, San Diego, 2011, Chap. 2), such lattices are significantly more uniform and have many more nearest neighbors than their Cartesian counterparts. Both of these facts make them far better suited for coordinating GPS algorithms, as demonstrated here in a variety of numerical tests.

Shielding effects in polymer–polymer reactions, 3. Z-RAFT star polymerization under various solvent conditions

Shielding effects of the surrounding arms and the chain on the encounter probability of reactive sites taking part in the Z-RAFT star polymerization are investigated (a) by use of lattice based Monte Carlo simulations in combination with exact enumeration techniques and (b) by direct simulation applying an off-lattice coarse-grained molecular dynamics method (dissipative particle dynamics, DPD). Making use of the former method the chain-length dependence of the shielding factors is discussed for a broad range of thermodynamic conditions and compared to DPD results for the athermal (good solvent) and theta (bad solvent) case, i.e., for the limiting solvent qualities evaluated. In addition, changes of the size and shape of the reaction partners on approach and penetration are discussed in some detail. The results of both simulation methods fairly well coincide and reveal that shielding is smaller and chain-length dependence less pronounced under theta conditions as compared to good solvent conditions. Experimentally determined polydispersities of polystyrene generated by Z-RAFT star polymerizations in the poor solvent cyclohexane were found to be smaller than with the good solvent toluene, which is in full accordance to the theoretical predictions.

DYNAMIC KNOWLEDGE EXTRACTION FROM SOFTWARE SYSTEMS USING SEQUENTIAL PATTERN MINING

Software system analysis for identifying software functionality in source code remains a major problem in the reverse engineering literature. The early approaches for extracting software functionality mainly relied on static properties of software system. However, the static approaches by nature suffer from the lack of semantic and hence are not appropriate for this task. This paper presents a novel technique for dynamic analysis of software systems to identify the implementation of certain software functionality known as software features. In the proposed approach, a specific feature is shared by a number of task scenarios that are applied on the software system to generate execution traces. The application of a sequential pattern mining technique on the generated execution traces allows us to extract execution patterns that reveal the specific feature functionality. In a further step, the extracted execution patterns are distributed over a concept lattice to separate feature-specific group of functions from commonly used group of functions. The use of lattice also allows for identifying a family of closely related features in the source code. Moreover, in this work we provide a set of metrics for evaluating the structural merits of the software system such as component cohesion and functional scattering. We have implemented a prototype toolkit and experimented with two case studies Xfig drawing tool and Pine email client with very promising results.

On an attack on RSA with small CRT-exponents

This paper concerns the RSA system with private CRT-exponents. Since Chinese remainder representation provides efficiency in computation, such system is of some practical significance. In this paper, an existing attack to small private CRT-exponents is analyzed. It is indicated that this attack makes nice use of lattice in RSA analysis, but some argument does not hold in general. Several counterexamples are constructed. Refinements and more precise statements of the attack are given.