Avalanche Impact Research Articles

High drain field impact ionization transistors as ideal switches

Impact ionization effect has been demonstrated in transistors to enable sub-60 mV dec−1 subthreshold swing. However, traditionally, impact ionization in silicon devices requires a high operation voltage due to limited electrical field near the device drain, contradicting the low energy operation purpose. Here, we report a vertical subthreshold swing device composed of a graphene/silicon heterojunction drain and a silicon channel. This structure creates a low voltage avalanche impact ionization phenomenon and leads to steep switching of the silicon-based device. Experimental measurements reveal a small average subthreshold swing of 16 µV dec−1 over 6 decades of drain current and nearly hysteresis-free, and the operating voltage at which a vertical subthreshold swing occurs can be as low as 0.4 V at room temperature. Furthermore, a complementary silicon-based logic inverter is experimentally demonstrated to reach a voltage gain of 311 at a supply voltage of 2 V.

Modified Playfair for Text File Encryption and Meticulous Decryption with Arbitrary Fillers by Septenary Quadrate Pattern

Cryptography secures data and serves to ensure the confidentiality of records. Playfair is a cryptographic symmetrical algorithm that encrypts statistics based on key costs. This secret is shared with an authorized person to retrieve data. In the conventional pattern, there is an area complexity and deficiency in letters, numbers, and special characters. This hassle has been overcome in previous studies by editing pattern dimensions. The fillers used throughout the enciphering were not eliminated during the retrieval process, which resulted in the indiscrimination of the retrieved statistics. The proposed method uses a separate quadrate pattern that strengthens the Playfair cipher and guarantees that the fillers are eliminated to ensure the authentic retrieval of records. The fillers indiscriminate and strengthen the set of rules in opposition to brute force and avalanche impact. The proposed algorithm was evaluated with a minimal change in the key, and was found to have an avalanche effect between 65% and 93.7%. The encrypted document is further encoded using the Lempel–Ziv–Markov chain algorithm (LZMA) to provide compressed second-level secured text with a compression ratio of 0.75 for a file size of 100 KB. The pattern was designed to subsidize the integrated characters found on the keyboard.

Physical vulnerability of reinforced concrete buildings under debris avalanche impact based on GF-discrepancy and DEM-FEM

Physical vulnerability of reinforced concrete buildings under debris avalanche impact based on GF-discrepancy and DEM-FEM

A NEW PROPOSED LIGHTWEIGHT CIPHER

Modern cryptography algorithm development has favored hardware optimization in computer systems. This is especially important for fitting cryptographic protocols onto devices with limited computing capacity, volume, and power consumption. Lightweight cryptography is an intellectual pursuit that develops cryptographic methods for economically frugal systems. This study introduces a revolutionary lightweight block cipher based on bio features for adequate cryptographic data security. A carefully planned sequence of analytical paradigms, the core of which involves complex computations to evaluate the proposed cryptographic approach, supports this innovation's theoretical foundations. As detailed in the research, these extensive assessments demonstrate the technology's strong security. The essay examines frequency analysis, frequency within block analysis, and the run test to provide a more complete review. These analytical tools provide sophisticated information regarding the algorithm's resilience to specific cryptographic vulnerabilities. Frequency analysis measures value distribution in the cipher, revealing possible susceptibilities. Frequency within block analysis shows complex value patterns inside discrete blocks, indicating the algorithm's behavior under certain situations. The run test is essential for determining the algorithm's avalanche impact. A careful evaluation of sequential value distribution tests the algorithm's innate sensitivity to input changes, a prerequisite for cryptographic security. This paper carefully examines cryptography algorithmic assessment following academic abstract principles. It includes core security assessments, frequency, frequency within the block, and run tests. The proposed lightweight block cipher's evaluative rigor supports its merit and cogency, making it a significant contribution to the evolving landscape of cryptographic algorithms for resource-constrained computational ecosystems.

Modeling Potential Glacial Lake Outburst Flood Process Chains and Effects From Artificial Lake‐Level Lowering at Gepang Gath Lake, Indian Himalaya

AbstractGlacial lake outburst floods (GLOFs) are a severe threat to communities in the Himalayas; however, GLOF mitigation strategies have been implemented for only a few lakes, and future changes in hazard are rarely considered. Here, we present a comprehensive assessment of current and future GLOF hazard for Gepang Gath Lake, Western Himalaya, considering rock and/or ice avalanches cascading into the lake. We consider ground surface temperature and topography to define avalanche source zones located in areas of potentially degrading permafrost. GLOF process chains in current and future scenarios, also considering engineered lake lowering of 10 and 30 m, were evaluated. Here, varied avalanche impact waves, erosion patterns, debris flow hydraulics, and GLOF impacts at Sissu village, under 18 different scenarios were assessed. Authors demonstrated that a larger future lake does not necessarily produce larger GLOF events in Sissu, depending, among other factors, on the location from where the triggering avalanche initiates and strikes the lake. For the largest scenarios, 10 m of lowering reduces the high‐intensity zone by 54% and 63% for the current and future scenarios, respectively, but has little effect on the medium‐intensity flood zone. Even with 30 m of lake lowering, the Sissu helipad falls in the high‐intensity zone under all moderate‐to‐large scenarios, with severe implications for evacuations and other emergency response actions. The approach can be extended to other glacial lakes to demonstrate the efficiency of lake lowering as an option for GLOF mitigation and enable a robust GLOF hazard and risk assessment.

Dynamic mechanical responses of reinforced concrete pier to debris avalanche impact based on the DEM-FEM coupled method

Engineering accidents of bridge pier damage and collapse incurred by debris avalanches frequently occur in mountainous areas. This paper presented a three-dimensional DEM-FEM coupled numerical model with the aim of exploring the dynamic mechanical characteristics of a reinforced concrete (RC) bridge pier subjected to a debris avalanche. It allows for considering the debris avalanche particles' discreteness and the continuous medium's structural dynamic responses. Moreover, a steel-sand composite structure was introduced to shield the pier from the impacting damage. The coupled model, constructed in the LS-DYNA software, was described in detail as well as its validation. The complicated interaction mechanism between the debris avalanche and the RC pier was interpreted. The critical dynamic responses of the RC pier throughout the collision process were also analyzed. A detailed discussion of influential parameters indicates that the debris avalanche's dry density has the most significant effect on dynamic mechanical characteristics of the bridge pier. Moreover, the numerical simulation of the RC pier with a steel-sand composite protective structure impacted by the debris avalanche was performed, and the results indicate that the composite shield could provide superior anti-collision performances.

A novel of substitution-box design using PLL algorithms in magic cube

In most modern symmetric ciphers, substitution boxes are non-linear core components that provide robust security and confusion. The construction of active S-boxes has been hot object among safely experts. The goal is at build a cryptographically active S-box, number of researchers have built an S-Box using RNA, DNA, chaotic systems, etc. In this article, we used new approach to generate multiple S-Boxes based on the Permutation of Last Layer algorithms (PLL) to replacement the place (permutation) of the pieces generated from the Magic Cube and instead of using static S-Boxes, we can generate dynamic S-Boxes to use various S-Boxes in every round to add to confusion. When comparing the proposed algorithm with other searches and tests on it. We found it has achieved a high percentage of success comparable to the S-Box from chaotic and etc. The proposed design passes S-Box test criteria effectively, these tests: invertibility, completeness, avalanche, strict avalanche, and balanced are among S-Box test criteria. The results of the analysis show that the novel S-Box overrun each of these statistical tests, has a good avalanche impact, and thus can protect against a wide range of attacks. Because S-Box and its reverse take but smaller milliseconds to construct it ability be applied in a variety of lightweight applications

Laser dynamics in nonlinear transparent media with electron plasma generation: effects of electron–hole radiative recombinations

The performance of optical devices manufactured via laser micromachining on nonlinear transparent materials usually relies on three main factors, which are the characteristic laser parameters (i.e. the laser power, pulse duration and pulse repetition rate), the characteristic properties of host materials (e.g. their chromatic dispersions, optical nonlinearities or self-focusing features) and the relative importance of physical processes such as the avalanche impact ionization, multiphoton ionization and electron–hole radiative recombination processes. These factors act in conjunction to impose the regime of laser operation; in particular, their competition determines the appropriate laser operation regime. In this work a theoretical study is proposed to explore the effects of the competition between multiphoton absorption, plasma ionization and electron–hole radiative recombination processes on the laser dynamics in transparent materials with Kerr nonlinearity. The study rests on a model consisting of a K-order nonlinear complex Ginzburg–Landau equation, coupled to a first-order equation describing time variation of the electron plasma density. An analysis of the stability of continuous waves, following the modulational instability approach, reveals that the combination of multiphoton absorption and electron–hole radiative recombination processes can be detrimental or favorable to continuous-wave operation, depending on the group-velocity dispersion of the host medium. Numerical simulations of the model equations in the fully nonlinear regime reveal the existence of pulse trains, the amplitudes of which are enhanced by the radiative recombination processes. Numerical results for the density of the induced electron plasma feature two distinct regimes of time evolution, depending on the strength of the electron–hole radiative recombination processes.

Mechanisms of slab avalanche release and impact in the Dyatlov Pass incident in 1959

The Dyatlov Pass incident is an intriguing unsolved mystery from the last century. In February 1959, a group of nine experienced Russian mountaineers perished during a difficult expedition in the northern Urals. A snow avalanche hypothesis was proposed, among other theories, but was found to be inconsistent with the evidence of a lower-than-usual slope angle, scarcity of avalanche signs, uncertainties about the trigger mechanism, and abnormal injuries of the victims. The challenge of explaining these observations has led us to a physical mechanism for a slab avalanche caused by progressive wind-blown snow accumulation on the slope above the hikers’ tent. Here we show how a combination of irregular topography, a cut made in the slope to install the tent and the subsequent deposition of snow induced by strong katabatic winds contributed after a suitable time to the slab release, which caused severe non-fatal injuries, in agreement with the autopsy results.

An optical chip for self-testing quantum random number generation

We present an implementation of a semi-device-independent protocol of the generation of quantum random numbers in a fully integrated silicon chip. The system is based on a prepare-and-measure scheme, where we integrate a partially trusted source of photons and an untrusted single photon detector. The source is a silicon photomultiplier, which emits photons during the avalanche impact ionization process, while the detector is a single photon avalanche diode. The proposed protocol requires only a few and reasonable assumptions on the generated states. It is sufficient to measure the statistics of generation and detection in order to evaluate the min-entropy of the output sequence, conditioned on all possible classical side information. We demonstrate that this protocol, previously realized with a bulky laboratory setup, is totally applicable to a compact and fully integrated chip with an estimated throughput of 6 kHz of the certified quantum random bit rate.

Design and simulation of 3C-SiC vertical power MOSFETs

ABSTRACT This paper reports on the design and simulation of 3C-SiC low-doped drain power MOSFETs, including key parameters such as the avalanche impact ionisation model and its relation to the breakdown voltage, the doping dependence of the bulk mobility, and the relationship between the on-resistance and breakdown voltage. A set of MOSFETs with different blocking layer doping were designed while scaling the parasitic JFET. A stepped doping profile is used to minimise localised breakdown at the p-well/n-type drift layer interface. The characteristics of the MOSFETs were obtained using a commercially available 2D simulation program. 2D Simulation results show good agreement with 1D model of the on-state resistance and current-voltage characteristics. The deviation from the experimental data may be due to using different designs and or may be due to the presence of surface charges excluded from 2D simulations and 1D quadratic model. Simulation results indicate that, for the chosen material parameters, a 600 V, 3C-SiC MOSFET with a thinned substrate, containing a drift-layer of 7 μm and a blocking layer doping density of 1 × 1016 cm−3, can have an on-state resistance of 0.8 mΩ-cm2.

Algebraic Construction of Powerful Substitution Box

The development of wireless transmission, day by day contacts the new statures of innovation. Cryptography is one of the procedures used to give security to information streaming over the system by encryption and decryption. Substitution box (S-box) is a one of a kind nonlinear activity in Advanced Encryption Standard (AES), this paper proposed a new algebraic approach to build the multifaceted nature of S-box by changing the affine transformation. This builds the affine change period to end up 102 and expands the security of the S-box against algebraic attacks and interpolation attacks. Further examination has uncovered that the Operational multifaceted nature of the power S-box is higher than the essential S-box. the proposed powerful S-box satisfies the ideal property of Avalanche's impact and has more prominent security towards linear and differential cryptanalysis. New S-box acquires all focal points and efficiency of any current advanced usage of AES S-box

Decoupling the Role of Inertia, Friction, and Cohesion in Dense Granular Avalanche Pressure Build‐up on Obstacles

Understanding the physical processes involved in snow avalanche‐obstacle interaction is essential to be able to estimate the pressure exerted on structures. Although avalanche impact pressure has been measured in field experiments for decades, the underlying physical principles are still elusive. Previous studies suggest that pressure is increased due to the formation of an influenced flow region around the structure, the mobilized domain, which varies in size depending on snow properties such as snow cohesion. Here, we aim to better understand how cohesion, friction, velocity, and their interplay affect avalanche pressure buildup on structures. This is achieved by simulating the avalanche‐obstacle interaction with a newly developed numerical model based on the discrete element method, using a cohesive bond contact law. The relevance of the model is tested by comparing simulated impact pressures with field measurements from the Vallée de la Sionne experimental site. Our results show that at the macroscale, impact pressure consists of the inertial, frictional, and cohesive contributions. The inertial and frictional contributions arise due to the existence, shape, and dimension of the mobilized domain. The cohesive contribution increases the particle contact forces inside the domain, leading up to a doubling of the pressure. Based on these physical processes, we propose a novel scaling law to reduce the problem of calculating the pressure induced by cohesive flows, to the calculation of cohesionless flows. These findings enhance our understanding of the interaction of cohesive granular flows, such as snow avalanches, and structures at the microscale and macroscale.

Snow Avalanche Impact Measurements at the Seehore Test Site in Aosta Valley (NW Italian Alps)

In full-scale snow avalanche test sites, structures such as pylons, plates, or dams have been used to measure impact forces and pressures from avalanches. Impact pressures are of extreme importance when dealing with issues such as hazard mapping and the design of buildings exposed to avalanches. In this paper, we present the force measurements recorded for five selected avalanches that occurred at the Seehore test site in Aosta Valley (NW Italian Alps). The five avalanches were small to medium-sized and cover a wide range in terms of snow characteristics and flow dynamics. Our aim was to analyze the force and pressure measurements with respect to the avalanche characteristics. We measured pressures in the range of 2 to 30 kPa. Though without exhaustive measurements of the avalanche flows, we found indications of different flow regimes. For example, we could appreciate some differences in the vertical profile of the pressures recorded for wet dense avalanches and powder ones. Being aware of the fact that more complete measurements are necessary to fully describe the avalanche flows, we think that the data of the five avalanches triggered at the Seehore test site might add some useful information to the ongoing scientific discussion on avalanche flow regimes and impact pressure.

Two Feistel rounds in image cryptography acting at the nucleotide level exploiting dna and rna property

In recent years, a variety of chaos-based image encryption algorithm have been proposed. The majority of image encryption systems, employ the confusion-diffusion architecture and operate at the pixel level. In this paper, a new color image encryption algorithm at the nucleotide-level applied, will be proposed. The first block will be altered by confusion with a boot vector generated from the clear image. After that, two Feistel rounds will be imposed on each 12 nucleotides clear block. The first round is performed by chaotic displacement of the nucleotides, and, the second uses a confusion matrix created in preconceived designs from chaotic maps used. Ultimately, a diffusion will be implemented to maximize the avalanche impact and keep the system out of differential attacks. On output, a transition to the nucleotides complementary will be established, and a confusion with the chaos vector will be developed. Next, the RNA application can be used to synthesize amino acids, and as a result, the isolation of the exon genes from introns. Simulations made on a large database with images in a variety of sizes and formats, show that our strategy can be prevented from being attacked by any known attack.

Recent Progress on Photomultiplication Type Organic Photodetectors

AbstractPhotodetectors as a significant unit of intelligent optoelectronic systems have stimulated immense attention from multidisciplinary areas. Photomultiplication (PM) is desirable for sensitive photodetectors with strong detection capability of weak light, which can further simplify the photo‐detection systems without pre‐amplifier circuit. For organic photodetectors (OPDs), PM phenomenon cannot be realized by utilizing the principle of avalanche effect or impact ionization as in inorganic materials, stemming from organic semiconductor materials with large exciton binding energy and disordered structure. In this review, the recent progress on PM type OPDs is comprehensively summarized from the perspective of device physics and material science. Charge tunneling injection induced by interfacial traps becomes the mainstream working mechanism for obtaining PM phenomenon. A series of PM type OPDs was achieved by utilizing interfacial blocking layer and introducing trap states into active layer or interfacial layer. The filter‐free PM type narrowband OPDs are realized by combining the concept of charge injection narrowing with the mechanism of PM. Meanwhile, further development on this hot topic is proposed and fully discussed, including multifunctional OPDs, organic–inorganic hybrid photodetectors, and photodetector systems.

Dynamics of avalanche-generated impulse waves: three-dimensional hydrodynamic simulations and sensitivity analysis

Abstract. This paper studies the lake dynamics for avalanche-triggered glacial lake outburst floods (GLOFs) in the Cordillera Blanca mountain range in Ancash, Peru. As new glacial lakes emerge and existing lakes continue to grow, they pose an increasing threat of GLOFs that can be catastrophic to the communities living downstream. In this work, the dynamics of displacement waves produced from avalanches are studied through three-dimensional hydrodynamic simulations of Lake Palcacocha, Peru, with an emphasis on the sensitivity of the lake model to input parameters and boundary conditions. This type of avalanche-generated wave is an important link in the GLOF process chain because there is a high potential for overtopping and erosion of the lake-damming moraine. The lake model was evaluated for sensitivity to turbulence model and grid resolution, and the uncertainty due to these model parameters is significantly less than that due to avalanche boundary condition characteristics. Wave generation from avalanche impact was simulated using two different boundary condition methods. Representation of an avalanche as water flowing into the lake generally resulted in higher peak flows and overtopping volumes than simulating the avalanche impact as mass–momentum inflow at the lake boundary. Three different scenarios of avalanche size were simulated for the current lake conditions, and all resulted in significant overtopping of the lake-damming moraine. Although the lake model introduces significant uncertainty, the avalanche portion of the GLOF process chain is likely to be the greatest source of uncertainty. To aid in evaluation of hazard mitigation alternatives, two scenarios of lake lowering were investigated. While large avalanches produced significant overtopping waves for all lake-lowering scenarios, simulations suggest that it may be possible to contain waves generated from smaller avalanches if the surface of the lake is lowered.

Modeling a glacial lake outburst flood process chain: the case of Lake Palcacocha and Huaraz, Peru

Abstract. One of the consequences of recent glacier recession in the Cordillera Blanca, Peru, is the risk of glacial lake outburst floods (GLOFs) from lakes that have formed at the base of retreating glaciers. GLOFs are often triggered by avalanches falling into glacial lakes, initiating a chain of processes that may culminate in significant inundation and destruction downstream. This paper presents simulations of all of the processes involved in a potential GLOF originating from Lake Palcacocha, the source of a previously catastrophic GLOF on 13 December 1941, killing about 1800 people in the city of Huaraz, Peru. The chain of processes simulated here includes (1) avalanches above the lake; (2) lake dynamics resulting from the avalanche impact, including wave generation, propagation, and run-up across lakes; (3) terminal moraine overtopping and dynamic moraine erosion simulations to determine the possibility of breaching; (4) flood propagation along downstream valleys; and (5) inundation of populated areas. The results of each process feed into simulations of subsequent processes in the chain, finally resulting in estimates of inundation in the city of Huaraz. The results of the inundation simulations were converted into flood intensity and preliminary hazard maps (based on an intensity-likelihood matrix) that may be useful for city planning and regulation. Three avalanche events with volumes ranging from 0.5 to 3 × 106 m3 were simulated, and two scenarios of 15 and 30 m lake lowering were simulated to assess the potential of mitigating the hazard level in Huaraz. For all three avalanche events, three-dimensional hydrodynamic models show large waves generated in the lake from the impact resulting in overtopping of the damming moraine. Despite very high discharge rates (up to 63.4 × 103 m3 s−1), the erosion from the overtopping wave did not result in failure of the damming moraine when simulated with a hydro-morphodynamic model using excessively conservative soil characteristics that provide very little erosion resistance. With the current lake level, all three avalanche events result in inundation in Huaraz due to wave overtopping, and the resulting preliminary hazard map shows a total affected area of 2.01 km2, most of which is in the high hazard category. Lowering the lake has the potential to reduce the affected area by up to 35 %, resulting in a smaller portion of the inundated area in the high hazard category.

Simulation of three-dimensional rapid free-surface granular flow past different types of obstructions using the SPH method

ABSTRACTIn nature, when hazardous geophysical granular flows (e.g. a snow avalanche) impact on an obstacle as they stream down a slope, rapid changes in flow depth, direction and velocity will occur. It is important to understand how granular material flows around such obstacles in order to enhance the design of defense structures. In this study, a three dimensional (3-D) Smoothed Particle Hydrodynamics (SPH) model is developed to simulate granular flow past different types of obstacles. The elastic–perfectly plastic model with implementation of the Mohr–Coulomb failure criterion is applied to simulate the material behavior, which describes the stress states of soil in the plastic flow regime. The model was validated by simulating the collapse of a 3-D column of sand with two different aspect ratios; the results showed that the SPH method is capable of simulating granular flow. The model is then applied to simulate the gravity-driven granular flow down an inclined surface obstructed by a group of columns with different spacing, a circular cylinder and a tetrahedral wedge. The numerical results are then compared with experimental results and two different numerical solutions. The good agreements obtained from these comparisons demonstrate that the SPH method may be a powerful method for simulating granular flow and can be extended to design protective structures.

3-D numerical approach to simulate the overtopping volume caused by an impulse wave comparable to avalanche impact in a reservoir

Abstract. The impact of an avalanche in a reservoir induces impulse waves, which pose a threat to population and infrastructure. For a good approximation of the generated wave height and length as well as the resulting overtopping volume over structures and dams, formulas, which are based on different simplifying assumptions, can be used. Further project-specific investigations by means of a scale model test or numerical simulations are advisable for complex reservoirs as well as the inclusion of hydraulic structures such as spillways. This paper presents a new approach for a 3-D numerical simulation of the avalanche impact in a reservoir. In this model concept the energy and mass of the avalanche are represented by accelerated water on the actual hill slope. Instead of snow, only water and air are used to simulate the moving avalanche with the software FLOW-3D. A significant advantage of this assumption is the self-adaptation of the model avalanche onto the terrain. In order to reach good comparability of the results with existing research at ETH Zürich, a simplified reservoir geometry is investigated. Thus, a reference case has been analysed including a variation of three geometry parameters (still water depth in the reservoir, freeboard of the dam and reservoir width). There was a good agreement of the overtopping volume at the dam between the presented 3-D numerical approach and the literature equations. Nevertheless, an extended parameter variation as well as a comparison with natural data should be considered as further research topics.