Regular Block Research Articles

Blockchain moderated by empty blocks to reduce the energetic impact of crypto-moneys

While cryptocurrencies and blockchain applications continue to gain popularity, their energy cost is evidently becoming unsustainable. In most instances, the main cost comes from the required amount of energy for the Proof-of-Work, and this cost is inherent to the design. In addition, useless costs from discarded work (e.g., the so-called Forks) and lack of scalability (in number of users and in rapid transactions) limit their practical effectiveness. In this paper, we present an innovative scheme which eliminates the nonce and thus the burden of the Proof-of-Work which is the main cause of the energy waste in cryptocurrencies such as Bitcoin. We prove that our scheme guarantees a tunable and bounded average number of simultaneous mining whatever the size of the population in competition, thus by making the use of nonce-based techniques unnecessary, achieves scalability without the cost of consuming a large volume of energy. The technique used in the proof of our scheme is based on the analogy of the analysis of a green leader election. The additional difference with Proof-of-Work schemes (beyond the suppression of the nonce field that is triggering most of the waste), is the introduction of (what we denote as) “empty blocks” which aim are to call regular blocks following a staircase set of values. Our scheme reduces the risk of Forks and provides tunable scalability for the number of users and the speed of block generation. We also prove using game theoretical analysis that our scheme is resilient to unfair competitive investments (e.g., ”51 percent” attack) and block nursing.

An Evaluation of Uncle Block Mechanism Effect on Ethereum Selfish and Stubborn Mining Combined With an Eclipse Attack

Ethereum accelerates the transaction process through a quicker block creation design. Since the time interval between the generation of blocks is very short (about 15s), block propagation time in an inefficient network is not negligible compared with the block time interval. This lead to the production of a large number of orphan blocks. In order to solve the security problems that may be caused by the orphan block and improve the transaction processing efficiency, Ethereum introduces the uncle block mechanism, i.e., an orphan block may get part of minted reward if it gets a reference by a regular block. In this paper, we show the weakness of the uncle block mechanism. Firstly, we describe the specific differences of Ethereum selfish and stubborn mining in every state from the ones in Bitcoin. Secondly, we simulate possible attacks, and the results show that the Ethereum selfish and stubborn mining strategies not only increase the reward of an attacker but also decrease the security threshold. The security threshold refers to the proportion of the attacker's computational power that needs to be achieved in order to obtain a higher reward than he should. In a practical network congestion rate, the security threshold are weakened to 0.129 and 0.216 against the Lead stubborn mining strategy and the original selfish mining strategy, respectively. When the congestion rate is rising, the reward is increasing and the threshold is decreasing. Thirdly, possible strategies are evaluated to find out the optimal one in different settings. Fourthly, we also extend the evaluation by combining three eclipse attack strategies with selfish or stubborn mining. Most of combinations bring more advantages to an attacker than a single strategy.

Development of a fluid-dynamical model (DFM) of the Yamal Novoportovsky oiland gas-condensing deposit (based on DFM seismic data interpretation)

Research subject. The idea of forecasting fluid-dynamical parameters is based on the views connecting the processes of sedimentation, tectonogenesis and fluid flows into an active fluid-dynamical model of the “sedimentary cover–basement” system. In such models, main fluid-dynamical parameters of oil and gas collectors, i.e. penetration and the vector of the fluid flow, are functionally connected with the components of the current state of the rock massif having a discrete (block) structure. These parameters can be calculated using DFM-interpretation technology developed by the authors in their previous works.Materials and methods. For the first time, DFM results are provided for the Yamal Novoportovsky oiland gas-condensing deposit. Here, the paleozoic basement stripped at a depth of 2700–3200 m is largely represented by metamorphic schists and marbled limestones. The basement has been covered by sediments and a platform cover since the early Jurassic age. The forecast of parameters describing modern geodynamical processes was performed on the basis of a comprehensive tectonophysical analysis of major geological and geophysical data.Results. The main axes of the neo-tectonic activity of the plate complex break the area under study into a quite regular block system that reflects a right-sided shift of fundamental blocks, that, in its turn predetermines the block shift in plate complex with the turn of the shift axis by 30 degrees. The most significant oil and gas holes in terms of influx demonstrate a connection with the described scheme of block activity. Thus, practically all high-debit boreholes were drilled in active axial zones.Conclusion. The proposed scheme of block activity satisfies the general principles of geodynamics. The developed model of abnormal pressure estimations by main productive intervals shows a good agreement with the distribution oiland gas boreholes in terms of productivity. Contact zones of active blocks present a particular interest from the standpoint of selecting the location of high-debit boreholes. These zones should be taken into account when developing new oil and gas deposits.

Investigating the electromagnetic wave-absorbing capacity and mechanical properties of flexible radar-absorbing knitted compound materials

This study fabricated flexible radar-absorbing knitted compound materials by weft knitting and blending ferromagnetic nickel micron-fibers and cotton fiber into structures with a concave–convex surface, including rhombic, mat, wavy, and leno stitches. The electromagnetic wave-absorbing capability and mechanical properties of the flexible radar-absorbing knitted compound materials were evaluated. The results showed that the rhombic, mat, and wavy stitches displayed high mechanical properties with high bursting strength and there were no significant differences among them. The rhombic stitch flexible radar-absorbing knitted compound material with a ferromagnetic nickel micron-fiber content of 14% had a maximum bandwidth of 13 GHz and achieved a minimum reflectance of −20 dB at 7 GHz, which was 150% that of mat fabric, and 200% that of wavy fabric and leno fabric. This was ascribed to the fact that the concave–convex surface with regular diamond-shaped block improved the dispersion of the electromagnetic wave, weakened the wave strength, and increased the interference. Therefore, the rhombic stitch flexible radar-absorbing knitted compound material was the most suitable for flexible radar-absorbing material in this study. The development of flexible radar-absorbing materials, by combining aerospace technology, military technology and textile technology, is important for the application in stealth of aircraft and weapons.

Out-of-plane seismic retrofitting of masonry walls with Textile Reinforced Mortar composites

Masonry walls are particularly vulnerable against out-of-plane seismic actions. Steel tie-bars and crowing beams in reinforced masonry can prevent their overturning, but collapse may take place also by bending, leaf separation or disaggregation. Textile Reinforced Mortar (TRM) composites, comprising high strength fabrics and inorganic matrices, can be applied to effectively improve the seismic capacity of masonry load-bearing walls and infill panels. Nevertheless, a deeper knowledge on the dynamic response and ultimate capacity of retrofitted walls still needs to be gained before TRM systems can be confidently used in engineering practice. This work describes a shake table test carried out on two full-scale wall specimens, one made of regular tuff blocks and one of two leaves of rubble stones, subjected to seismic out-of-plane vertical bending. The walls were tested unreinforced, repaired and strengthened with TRMs and tested again. A unidirectional textile of ultra high tensile strength steel was used on the tuff wall, whereas a bidirectional basalt mesh was applied over the entire surface of the stone wall, with the addition of transversal steel connectors. The responses of the specimens before and after retrofitting are compared to show the improvement of acceleration and displacement capacity entailed by TRM retrofitting and the modification of deflection profiles, failure modes, damage development and dynamic properties. Test outcomes prove the effectiveness of TRM composites for the protection of existing masonry structures, including architectural heritage, in earthquake prone areas and provide information on the reliability of analytical predictions for seismic assessment.

Study on the nucleation mechanism of hard particles in high boron and high carbon alloy by laser-induced arc welding

It is an effort to improve the phenomenon of thick boron-carbon compound forming, during the process of arc surfacing of high boron and high carbon alloy. This paper deals with the refinement of hard particles, in order to improve the microstructure of the surfacing layer. The comparison of microstructure and hard particles composition between laser arc composite surfacing layer and arc surfacing layer confirmed that hard particles of both are (Fe, Cr)7(B, C)3 and (Fe, Cr)2B. Also, the results show that in the cross section of the arc surfacing layer, the hard particles are in the shape of long strips, hexagonal and regular quadrangular blocks. But the size of hard particles decreases and follows a uniform distribution under laser induction. The wear resistance of laser arc composite surfacing layer is obviously improved. This may be due to that thick hard particles were broken into smaller units by pulsed laser stirring molten pool, thus providing more nucleating particles for the formation of hard particles. At the same time, the thick hard particles were melt down by high energy laser beam, which improves the temperature gradient and forces hard particles to grow uniformly.

Parental Perceptions of Year-Round School Environments

ABSTRACTYear-round school is the organization of days within a school calendar year to provide students with regular breaks and instructional blocks. This study surveyed 502 parents to identify factors influencing parental support for, or opposition to, year-round school. Three themes were constructed based on parent responses: children need educational enrichment in the summer, summertime provides essential opportunities for personal restoration, and summertime strengthens family relationships. The study findings illustrated the complexity of factors influencing parental perceptions of year-round school; parents both for and against year-round school identified similar factors, yet for different reasons. Implications and limitations are explored.

An analytic evaluation for the impact of uncle blocks by selfish and stubborn mining in an imperfect Ethereum network

Besides supporting smart contract, another Ethereum distinct feature lies in the improvement of running efficiency achieved by the uncle block mechanism. To mitigate network congestion, an orphan block has a chance to be referenced by a regular block as an uncle block rather than being abandoned directly. In this paper, we use a Markov state machine to model selfish and stubborn mining in an imperfect Ethereum network with natural forks. The security threshold against selfish mining, which indicates how difficult an attacker could gain more than he deserves, decreases to 23.8% in an uncle block rate of 11%. Two advanced selfish mining strategies, trail stubborn mining and equal fork combined with trail stubborn mining, are also analyzed with different uncle block rates in this paper. In different feasible regions, strategies that bring about the optimal reward vary from each other. All evaluations in this paper are carried out in an analytic method, which is more flexible and scalable than a numeric method if it combines multiple attacks or extends to several attackers.

A foamed cement blocks with paraffin/expanded graphite composite phase change solar thermal absorption material

When solar radiation reaches its peak value during the midday, buildings' external walls absorb the highest amount of heats and result in dramatic spikes in cooling load and energy consumption. To flatten the energy peak, promote energy efficiency, and preserve thermal comfort, this study developed a novel foamed thermal insulation cement block with extraordinary heat storage capacity. To prepare the proposed foamed cement block, a paraffin/expanded graphite composite phase change heat storage material with a phase transition temperature of 41.9 °C and an enthalpy value of 207.8 J/g was used to load paraffin into expanded graphite in a water bath at 44 °C. After mixing the paraffin/expanded graphite composite phase change material (PCM) with cement, foams were added, stirred and poured into the mold to make a novel foaming cement thermal insulation block. Due to its porous structure, the foamed cement has lightweight as well as high heat preservation capacity. To investigate the characteristics of the proposed material, this investigated its physical structure, thermal conductivity, and heat energy storage performance when the material mass fractions of PCM are 10%, 15%, 20%, 25% and 30%, and regular (pure) cement blocks. The experimental results show that there is no chemical reaction during material preparation. In addition, composite materials’ PCM mass fraction and their thermal storage capacity increase simultaneously. The comprehensive analysis shows that foamed cement blocks with 30% PCM contents have the best thermal energy storage performance and can maintain the lowest average indoor temperature. Therefore, the proposed foamed cement blocks can be applied to building outer surfaces and sandwiched middle enclosures to develop energy efficiency insulation walls.

Hierarchical quality-guided phase unwrapping algorithm.

A hierarchical quality-guided phase unwrapping algorithm in a shared memory environment is proposed. First, the wrapped phase is divided into regular blocks, and local wrap counts of every block are obtained by a quality-guided strategy. Then, the gradient of the block wrap counts of adjacent blocks and the quality of every block are defined by the boundary local wrap counts of every block. Each block's data can be regarded as an abstract phase point, and the quality-guided strategy can be used again to solve the block wrap counts of each block. Finally, the absolute wrap counts of each phase point are obtained by adding local wrap counts and corresponding block wrap counts, and then the final unwrapped phase is obtained. The performance of the proposed algorithm is verified through an unwrapping experiment performed on simulated data and the real interferometric synthetic aperture sonar wrapped phase in a shared memory environment. The results show that the proposed method greatly improves phase unwrapping efficiency while maintaining the correctness of unwrapped results.

New Chances for Old Towns. 21st Century Revitalization in Historic Centres of Silesia

Silesia is a region of Central Europe with a complex and multicultural history. Its borders and nationality has changed repeatedly over the centuries. Consequently, Silesia’s identity, culture and economy were shaped throughout the region’s history by Polish, Czech, Austrian, Prussian and German influences. Since 1945 Silesia has been located mostly in Poland. The majority of Silesian towns was founded in the Middle Ages creating a regular system of a settlement network in the entire region. This process started at the beginning of the 13th century and was a part of dynamic urbanization of the entire Europe. The basic features of Silesian medieval urban structures, known presently as the Old Towns, are: an orderly plan, chequered grid of streets, regular blocks of development and a centrally located market square. Throughout the centuries historic towns in Silesia remained within their city walls, undergoing changes, rather than simply developing. It was only the 19th century that brought favourable circumstances for development. Unfortunately, as a result of the World War II, many Silesian historic centres were significantly damaged. After the period of the post-war rebuilding, the old towns in Silesia experienced a process of degradation resulting from the political and economic system of Poland in that period. The first possibilities to raise the quality of the old town areas appeared after the year 1989 with the Polish political transformation. In the 21st century, mainly thanks to EU funds, numerous projects were implemented within the historic town centres of Silesia in the field of urban revitalization. The study presents the range and specificity of these activities undertaken and the review of the selected completed projects. The results help not only to assess the effects of the actions undertaken and their impact on the quality of urban living conditions, but to relate them to the towns’ identities and their spatial uniqueness as well. Finally, the work is an attempt to answer the question to what extent a new life has been breathed to historic old town structures in Silesia. The analyses are based to a large extend on the Regional Operational Programmes elaborated in the years 2007-2013 in 4 administrative units, which form in various proportions the region of Silesia.

A block form of a singular pencil of operators and a method of obtaining it

A block form of a singular operator pencil $\lambda A+B$, where $\lambda$ is a complex parameter, and the linear operators $A$, $B$ act in finite-dimensional spaces, is described. An operator pencil $\lambda A+B$ is called regular if $n = m = rk(\lambda A+B)$, where $rk(\lambda A+B)$ is the rank of the pencil and $m$, $n$ are the dimensions of spaces (the operators map an $n$-dimensional space into an $m$-dimensional one); otherwise, if $n \ne m$ or $n = m$ and $rk(\lambda A+B)<n$, the pencil is called singular (irregular). The block form (structure) consists of a singular block, which is a purely singular pencil, i.e., it is impossible to separate out a regular block in this pencil, and a regular block. In these blocks, zero blocks and blocks, which are invertible operators, are separated out. A method of obtaining the block form of a singular operator pencil is described in detail for two special cases, when $rk(\lambda A+B) = m < n$ and $rk(\lambda A+B) = n < m$, and for the general case, when $rk(\lambda A+B) < n, m$. Methods for the construction of projectors onto subspaces from the direct decompositions, relative to which the pencil has the required block form, are given. Using these projectors, we can find the form of the blocks and, accordingly, the block form of the pencil. Examples of finding the block form for the various types of singular pencils are presented. To obtain the block form, in particular, the results regarding the reduction of a singular pencil of matrices to the canonical quasidiagonal form, which is called the Weierstrass-Kronecker canonical form, are used. Also, methods of linear algebra are used. The obtained block form of the pencil and the corresponding projectors can be used to solve various problems. In particular, it can be used to reduce a singular semilinear differential-operator equation to the equivalent system of purely differential and purely algebraic equations. This greatly simplifies the analysis and solution of differential-operator equations.

Building Earthquake Damage Analysis Using Terrestrial Laser Scanning Data

Terrestrial laser scanners (TLSs) can acquire high‐precision three‐dimensional point cloud data for earthquake‐damaged buildings. In this study, we collected TLS data in the Wenchuan earthquake zone and developed the TLS‐BSAM (terrestrial laser scanning‐based building shape analysis model) to carry out a building earthquake damage analysis. This model involves equidistance polygon array extraction, shape dispersion parameter calculations, irregular building clustering segmentation, and damage analysis. We chose 21 buildings as samples for the experiments. The results show that when using an equidistance polygon array to depict a three‐dimensional building, 0.5 m is a reasonable sampling interval for building earthquake damage analysis. Using certain characteristic parameters to carry out K‐means clustering, one can efficiently divide irregular buildings into regular blocks. Then, by weighted averages, the shape dispersion parameters can be calculated to express the damage extent to buildings. Among the shape dispersion parameters, at least the weighted average standard deviations of the tilt direction, rectangularity, compactness, and center point are suitable to reflect the damage extent. Higher values reflect more serious damage. On the basis of existing data, the weighted average standard deviations of the tilt direction and center point can be used to establish discriminant functions that can effectively distinguish the damage extent.

Electrocardiographic diagnosis: “Regular block”!

Electrocardiographic diagnosis: “Regular block”!

Efficiency of Neighbouring Designs for First Order Correlated Models

The comparison of efficiency of Complete and Incomplete Nearest Neighbour Balanced Block Designs over regular block design using average variance, generalized variance and min-max variance with the error term e given in the NNBD model follows using first order correlated models. It is observed that, RH and RD show increasing efficiency values for direct and neighbour effects (left and right) for MA(1) models. The RA and RG show neither increasing nor decreasing efficiency values are observed for direct and neighbouring effects for AR(1) and MA(1) models. In the case of ARMA(1,1) model, neither increasing nor decreasing efficiency values have been observed for average variance and generalized variance. The RE shows decreasing efficiency values with p in the interval 0.1 to 0.4 for direct and neighbouring effects for AR(1), MA(1) and ARMA(1,1) models.

Mesoscopic structure PFC∼2D model of soil rock mixture based on digital image

Soil-rock mixture (S/RM) is a very complex discontinuous medium material, which is a multiphase system consisting of high strength rock blocks (Rocks), relatively soft filling components (Soils) and corresponding pores. Because the mechanical properties of various components of soil-rock mixtures under external loads are very different, and there are extremely complex interactions between them. Therefore, the mechanical properties of this geotechnical material (such as stress transfer, failure mode, crack propagation, bearing capacity, etc.) are quite different from those of homogeneous geotechnical materials, and largely depend on the internal structure characteristics of soil-rock mixtures (such as particle size composition, particle shape, particle distribution and arrangement). Due to the complexity of the model, the simulation of its meso-mechanical properties is mostly confined to the random simulation of regular blocks. In this paper, an automatic generation method of PFC∼2D numerical model of soil-rock mixture microstructure based on digital image processing is proposed, and the experimental simulation is carried out with matlab. Thus, the rapid, real and automatic modeling of heterogeneous material microstructure by PFC∼2D software is realized. The PFC∼2D numerical calculation model of soil-rock mixtures is established. The results show that when the stone content is 80%, the analysis should be caused by the large amount of rock, which leads to the large internal voids, and the sudden unloading between the rock and the rock during compaction and then the structural reorganization.

Fabrication and electrochemical characteristics of NCM-based all-solid lithium batteries using nano-grade garnet Al-LLZO powder

Garnet-related Li6.25Al0.25La3Zr2O12 (Al-LLZO) powder was prepared by calcination the precursor synthesized a Couette–Taylor reactor. The powder comprised regular blocks (1–2μm) and consisted of fine particles (average particle size: D50=600nm, specific surface area: 2.42m2g−1) that adopted a highly crystalline nanoscale cubic structure (lattice parameter: a=13.07769Å; crystallite size: 41.4nm). A composite electrolyte (CE) sheet in which the Al-LLZO nanopowder was finely dispersed was prepared by casting a slurry comprising 70wt% Al-LLZO, polyethylene oxide (PEO), and lithium salt (LiClO4). The total ionic conductivity of the CE sheet was 7.59×10−6Scm−1 at 25°C and 1.93×10−3Scm−1 at 70°C, compared with 3.03×10−4Scm−1 at 25°C for the Al-LLZO pellet. Cyclic voltammetry showed that the electrochemical potential of the CE sheet was superior to that of PEO sheet. For application of the CE in all-solid lithium batteries (ASLBs), a composite NCM-based cathode composed of Al-LLZO, PEO, Super-P, and VGCF was also prepared. The discharge capacity of the cell was ∼122mAhg−1 at 0.1C & 70°C in voltages of 3.0–4.1V, and ∼80% of the initial capacity was maintained over 100 cycles with high rate characteristics.

31 EPID response modeling with Monte Carlo for Novalis TrueBeam STx

Introduction Portal Dosimetry is a very convenient tool to perform patient QA for VMAT plan with TrueBeam STx Linac. On the other hand, it is not sensitive to gantry rotation. Monte Carlo modeling of EPID response could offer an alternative to the PDIP (portal dosimetry prediction algorithm) in Eclipse. It also opens wider perspectives: response prediction with phantom or patient. Preliminary work focuses on PSF (point spread function) fitting, and verification against measurements. Methods As we cannot irradiate EPID with a very narrow ( Monte Carlo calculation of the EPID response is performed with PenEasy. A Phase Space is obtained after collimator from PRIMO. This phase space can then be handled by PenEasy (including EPID spread function), with simple object in the beam path. Results The sharpest transition from blocked to open beam is obtained using metal blocks behind EPID. A.Latorre showed that best fit to experimental results is obtained with modified Lorentzian model (with FWHM = 0.74 mm). This model fits well the steepest part of the penumbra. Minor deviation ( 5%) occurs in the furthest region under open beam. This model does not fit under the blocked area (probably due to block transmission/scattering). Ongoing step is to measure EPID response with simple regular shaped PMMA blocks. Conclusions Monte Carlo simulation (combining PRIMO, PenEasy and fitted EPID spread function) offers the perspective of predicting EPID response for TrueBeam STx linac. It can be used as an alternative to PDIP algorithm. Using it with anisotropic phantom could make Portal Dosimetry sensitive to gantry rotation. Using it in vivo may allow to check patient positioning against CT positioning in TPS.

Finite-dimensional representations of minimal nilpotent W-algebras and zigzag algebras

Let g \frak g be a simple finite-dimensional Lie algebra over an algebraically closed field F \mathbb F of characteristic 0. We denote by U ( g ) \mathrm {U}(\frak g) the universal enveloping algebra of g \frak g . To any nilpotent element e ∈ g e\in \frak g one can attach an associative (and noncommutative as a general rule) algebra U ( g , e ) \mathrm {U}(\frak g, e) which is in a proper sense a “tensor factor” of U ( g ) \mathrm {U}(\frak g) . In this article we consider the case in which e e belongs to the minimal nonzero nilpotent orbit of g \frak g . Under these assumptions U ( g , e ) \mathrm {U}(\frak g, e) was described explicitly in terms of generators and relations. One can expect that the representation theory of U ( g , e ) \mathrm {U}(\frak g, e) would be very similar to the representation theory of U ( g ) \mathrm {U}(\frak g) . For example one can guess that the category of finite-dimensional U ( g , e ) \mathrm {U}(\frak g, e) -modules is semisimple. The goal of this article is to show that this is the case if g \frak g is not simply-laced. We also show that, if g \frak g is simply-laced and is not of type A n A_n , then the regular block of finite-dimensional U ⁡ ( g , e ) \operatorname {U}(\frak g, e) -modules is equivalent to the category of finite-dimensional modules of a zigzag algebra.

How Reliable are Compositions of Series and Parallel Networks Compared with Hammocks?

A classical problem in computer/network reliability is that of identifying simple, regular and repetitive building blocks (motifs) which yield reliability enhancements at the system-level. Over time, this apparently simple problem has been addressed by various increasingly complex methods. The earliest and simplest solutions are series and parallel structures. These were followed by majority voting and related schemes. For the most recent solutions, which are also the most involved (e.g., those based on Harary and circulant graphs), optimal reliability has been proven under particular conditions. 
 Here, we propose an alternate approach for designing reliable systems as repetitive compositions of the simplest possible structures. More precisely, our two motifs (basic building blocks) are: two devices in series, and two devices in parallel. Therefore, for a given number of devices (which is a power of two) we build all the possible compositions of series and parallel networks of two devices. For all of the resulting twoterminal networks, we compute exactly the reliability polynomials, and then compare them with those of size-equivalent hammock networks. The results show that compositions of the two simplest motifs are not able to surpass size-equivalent hammock networks in terms of reliability. Still, the algorithm for computing the reliability polynomials of such compositions is linear (extremely effcient), as opposed to the one for the size-equivalent hammock networks, which is exponential. Interestingly, a few of the compositions come extremely close to size-equivalent hammock networks with respect to reliability, while having fewer wires.a