Entire Path Research Articles

Matrix calculations for moments of Markov processes

AbstractMatryoshka dolls, the traditional Russian nesting figurines, are known worldwide for each doll’s encapsulation of a sequence of smaller dolls. In this paper, we exploit the structure of a new sequence of nested matrices we callmatryoshkan matricesin order to compute the moments of the one-dimensional polynomial processes, a large class of Markov processes. We characterize the salient properties of matryoshkan matrices that allow us to compute these moments in closed form at a specific time without computing the entire path of the process. This simplifies the computation of the polynomial process moments significantly. Through our method, we derive explicit expressions for both transient and steady-state moments of this class of Markov processes. We demonstrate the applicability of this method through explicit examples such as shot noise processes, growth–collapse processes, ephemerally self-exciting processes, and affine stochastic differential equations from the finance literature. We also show that we can derive explicit expressions for the self-exciting Hawkes process, for which finding closed-form moment expressions has been an open problem since their introduction in 1971. In general, our techniques can be used for any Markov process for which the infinitesimal generator of an arbitrary polynomial is itself a polynomial of equal or lower order.

On the structure of regularization paths for piecewise differentiable regularization terms

Regularization is used in many different areas of optimization when solutions are sought which not only minimize a given function, but also possess a certain degree of regularity. Popular applications are image denoising, sparse regression and machine learning. Since the choice of the regularization parameter is crucial but often difficult, path-following methods are used to approximate the entire regularization path, i.e., the set of all possible solutions for all regularization parameters. Due to their nature, the development of these methods requires structural results about the regularization path. The goal of this article is to derive these results for the case of a smooth objective function which is penalized by a piecewise differentiable regularization term. We do this by treating regularization as a multiobjective optimization problem. Our results suggest that even in this general case, the regularization path is piecewise smooth. Moreover, our theory allows for a classification of the nonsmooth features that occur in between smooth parts. This is demonstrated in two applications, namely support-vector machines and exact penalty methods.

Scalable and Flexible Traffic Steering for Service Function Chains

Network Function Virtualization (NFV) has inspired numerous orchestration algorithms to decide Virtualized Network Function (VNF) placement and routing paths for service requests with Service Function Chain (SFC) demands. With different optimization goals, these algorithms may select various routing paths for request flows. Nevertheless, existing traffic steering solutions either fail to fully support NFV Orchestrator (NFVO) in path selection, or result in low scalability in the underlay Software Defined Network (SDN). In this paper, we propose STAR to tackle both problems simultaneously. STAR divides the entire routing path for SFC request into several path segments, then performs Output-Port-based, Default-Path-based or RSP-ID-based traffic steering on each path segment. With the idea of path division and these traffic steering mechanisms, STAR achieves flexible traffic steering along any paths selected by NFVO and enables different Rendered Service Paths (RSPs) with the same path segments to share the same forwarding rules. In this way, STAR ensures the correct enforcement of path selection decisions from NFVO and significantly reduces forwarding rule consumption and control overhead. We evaluate STAR with the experiments on a real testbed and large-scale simulations. The results show that our framework is scalable in the SDN data plane and control plane (e.g., reducing rules in hardware switches by more than 70% compared with NSH-based solutions) while retaining the flexibility of steering traffic along any SFC routing paths to provide full support for path decision enforcement (e.g., achieving the highest path decision enforcement ratio in 11 of the 12 cases) with acceptable overhead.

Optimal fiscal policy under capital overaccumulation

AbstractIn a canonical model of heterogeneous agents with precautionary saving motives, Aiyagari [(1995) Journal of Political Economy103(6), 1158–1175.] breaks the classical result of zero capital tax obtained in representative-agent models. Aiyagari argues that with capital overaccumulation the optimal long-run capital tax should be strictly positive in order to achieve aggregate allocative efficiency suggested by the modified golden rule (MGR). In this paper, we find that, depending on the sources of capital overaccumulation, capital taxation may not be the most efficient means to restore the MGR when government debt is feasible. To demonstrate our point, we study optimal policy mix in achieving the socially optimal (MGR) level of aggregate capital stock in an infinite horizon heterogeneous-agents incomplete-markets economy where capital may be overaccumulated for two distinct reasons: (i) precautionary savings and (ii) production externalities. By solving the Ramsey problem analytically along the entire transitional path, we reveal that public debt and capital taxation play very distinct roles in dealing with the overaccumulation problem. The Ramsey planner opts neither to use a capital tax to correct the overaccumulation problem if it is caused solely by precautionary saving—regardless of the feasibility of public debt—nor to use debt (financed by consumption tax) to correct the overaccumulation problem if it is caused solely by production externality (such as pollution)—regardless of the feasibility of a capital tax. The key is that the MGR has two margins: an intratemporal margin pertaining to the marginal product of capital (MPK) and an intertemporal margin pertaining to the time discount rate. To achieve the MGR, the Ramsey planner needs to equate not only the private MPK with the social MPK but also the interest rate with the time discount rate—neither of which is equalized in a competitive equilibrium. Yet public debt and a capital tax are each effective only in calibrating one of the two margins, respectively, but not both.

Multi-Semantic Path Representation Learning for Travel Time Estimation

Travel time estimation of a given path is a crucial task of Intelligent Transportation Systems (ITS). Accurate travel time estimation can benefit multiple downstream applications such as route planning, real-time navigation, and urban construction. However, it is a challenging problem since the travel time is largely affected by multiple complicated factors including spatial factors, temporal factors and external factors, and obtaining informative representations of a given path is not trivial. Most previous works solved this problem in either Euclidean space or non-Euclidean space, which was unilateral to represent the actual traveling path and led to relatively poor performance. To address this, this paper proposes a multi-semantic path representation method to exploit information in Euclidean space and non-Euclidean space simultaneously. First, since the path is composed of several segments, we generate semantic representations of segments in non-Euclidean space by taking both the time information and the historical co-occurrence into consideration. Second, as the path could be equally represented as several travelled intersections, semantic representations of intersection sequences are also extracted to improve the capability of the method by considering information in Euclidean space. Meanwhile, semantic representations from properties, including the length and the type of segments, are also incorporated into the model. Finally, a sequence learning component is added on the top to aggregate the information along the entire path and provides the final estimation. Extensive experiments were conducted on two real-world taxi trajectories datasets, and the experimental results demonstrate the superiority of the proposed method.

Structure-Based Demystification of Radical Catalysis by a Coenzyme B12 Dependent Enzyme-Crystallographic Study of Glutamate Mutase with Cofactor Homologues.

Catalysis by radical enzymes dependent on coenzyme B12 (AdoCbl) relies on the reactive primary 5'-deoxy-5'adenosyl radical, which originates from reversible Co-C bond homolysis of AdoCbl. This bond homolysis is accelerated roughly 1012-fold upon binding the enzyme substrate. The structural basis for this activation is still strikingly enigmatic. As revealed here, a displaced firm adenosine binding cavity in substrate-loaded glutamate mutase (GM) causes a structural misfit for intact AdoCbl that is relieved by the homolytic Co-C bond cleavage. Strategically interacting adjacent adenosine- and substrate-binding protein cavities provide a tight caged radical reaction space, controlling the entire radical path. The GM active site is perfectly structured for promoting radical catalysis, including "negative catalysis", a paradigm for AdoCbl-dependent mutases.

Structure-Based Demystification of Radical Catalysis by a Coenzyme B12 Dependent Enzyme-Crystallographic Study of Glutamate Mutase with Cofactor Homologues.

Catalysis by radical enzymes dependent on coenzyme B12 (AdoCbl) relies on the reactive primary 5′‐deoxy‐5′adenosyl radical, which originates from reversible Co−C bond homolysis of AdoCbl. This bond homolysis is accelerated roughly 1012‐fold upon binding the enzyme substrate. The structural basis for this activation is still strikingly enigmatic. As revealed here, a displaced firm adenosine binding cavity in substrate‐loaded glutamate mutase (GM) causes a structural misfit for intact AdoCbl that is relieved by the homolytic Co−C bond cleavage. Strategically interacting adjacent adenosine‐ and substrate‐binding protein cavities provide a tight caged radical reaction space, controlling the entire radical path. The GM active site is perfectly structured for promoting radical catalysis, including “negative catalysis”, a paradigm for AdoCbl‐dependent mutases.

Characterization of beam ion loss in high poloidal beta regime on EAST

A critical issue for achieving the integrated operation of steady-state long-pulse high-confinement (H-mode) plasmas on experimental advanced superconducting tokamak (EAST) is to improve beam ion population confinement during neutral beam injection (NBI). To study the characterization of beam ion loss and improve beam ion confinement, the steady-state long pulse scenario discharges were conducted on EAST (β p ⩾ 2.0, β N ⩾ 1.7, q 95 ⩾ 6.7 and H 98y2 ⩾ 1.1) with NBI heating. Based on neutron yield, the beam voltage and line-averaged electron density were adjusted from 50 kV to 60 kV and 4.4 × 1019 m−3 to 5.0 × 1019 m−3, respectively. The results show that the dominant mechanisms of beam ion loss are shine-through loss, prompt loss, and stochastic ripple loss. The shine-through loss fraction is determined by initial velocity, flight time and entire beam path. The change in prompt loss fraction is caused by the change in the deposition of beam ions. The change in stochastic ripple loss fraction is caused by the change in the initial fraction of trapped-confined ions. Detailed physics shows that the prompt loss fraction during counter-Ip injections (∼45%) is far larger than during co-Ip injections (∼5%) due to the finite orbit width. The lost ions are mainly deposited on the lower divertor or below the midplane since the direction of magnetic drift is vertical down. The orbit types of prompt loss during counter-Ip injections are mainly trapped-lost and ctr-passing lost. To minimize the prompt loss fraction during counter-Ip injections, a reversed Ip configuration (rev-Ip) discharge #94758 was conducted. The result suggests that the beam ion wall load fraction during counter-Ip tangential injection (∼3%) is far lower than that in normal Ip configuration (nor-Ip) discharge #94820. It is also found that the confinement of beam ion population in the counter-Ip injection #94758 was greatly improved when compared to #94820. This study can provide unique support for the improvement of beam ion population confinement and for the performance evaluation of the NBI system on EAST and future tokamaks.

JUSTICE AS A CRITERION FOR THE VALUE OF LAW

The article studies the category of justice in law from the point of view of the value criterion. Purpose: to analyze justice in law from the point of view of the axiological approach in legal studies revealing the content of this category, to determine the value of justice, which is the basis of legal norms, legal relations, principles of law, that are relevant to regulating relations between the state, society and the individual. Methods: the authors apply descriptions, comparisons, dialectical logic, comparative-legal method. The category of justice is analyzed from the point of view of various approaches in law; it is shown that the axiological approach highlights the essence of justice and its importance for regulating relations between the state, society and the individual, the need to find a balance in regulating these relations. Results: it is concluded that the category of justice implies a direct examination of the attitude of society to the norms of law, to the real equality of different subjects of law, to law enforcement practice, the level of legal awareness of citizens and officials, implementing and enforcing laws. The study of justice in law touches all historical eras, the entire evolutionary path of law itself, is a method for creating legal reality and legal norms.

Analisa pengaruh jarak cutting torch terhadap permukaan berputar pada mesin pemotong kontur sambungan pipa

Currently steel pipes are needed, especially in construction work. Construction with pipe materials cannot be separated from the process of joining and cutting. The cutting process for large pipes always uses a thermal cutting process. This study aims to determine how much influence the cutting distance has on the cutting results on a pipe that rotates at a constant 0.8 rpm following the shape of the corner joint contour. To achieve the objectives of this study, a pipe cutting tool with a diameter of 4 to 6 inches is needed with the thermal cutting method using the Oxy Acetylene Cutting (OAC) process This research data was obtained by cutting the 4inch pipe schedule 10s, schedule 20s and schedule 40s in a rotating condition and the cutting torch moves back and forth. The pipe rotates at 0.8 rpm using an AC motor transmitted using a gearbox connected to the wheel as a holder where the pipe rotates. The results of the cutting are in the form of a pipe connection contour with an angle of 900 and 600. As the independent variable in this study was set the cutting distance is 5mm, 7mm and 10 mm, while the fixed variables are determined by cutting speed 280 mm/minute, acetylene gas pressure 3.5 kg/cm2 and oxygen 17.5 kg/cm2. In order to get effective results, preheat the surface of the pipe with a gas fuel mixture until it reaches the melting temperature of the pipe as the main ingredient. The cutting results that meet the entire path of the pipe can be cut completely and through and there is very little splash or melt dirt during the cutting process. After cutting, the best results are obtained at a cutting distance of 5 mm both on schedule 10s, schedule 20s and schedule 40s.

Feature-guided regularization parameter selection in sparse de-noising for fault diagnosis

Using the sparse and redundant representation model to de-noise vibration signals is an effective method for mechanical fault diagnosis. The selection of the regularization parameter in the sparse de-noising algorithm plays a vital role in reconstructing fault features. The current choices, however, are primarily based on fixed-form parameters derived under the assumption of additive white noise or based on the “trial and error” method. As a result, the extracted de-noised signals often fail to show fault features. To solve this difficulty, a self-adaptive regularization parameter selection strategy is proposed, which directly measures the significance of fault features in sparse de-noised signals. Firstly, the entire solution path is obtained by the computationally efficient least angle regression (LARS) algorithm. Besides, a feature presence probability index (FP) is well designed to measure the significance of fault features in the reconstructed signal envelope demodulation spectrum. Accordingly, with the help of the maximal FP indicator, the optimal regularization parameter and LARS solution is determined. The proposed method is not limited by noise probability distributions; therefore, it shows the superiority of extracting fault features in both the simulation and experimental data analysis.

Plateau Rayleigh instability of soft elastic solids. Effect of compressibility on pre and post bifurcation behavior

Solid surface tension can deform soft elastic materials at macroscopic length scales. At a critical surface tension, elastocapillary instabilities in soft filaments emerge that resemble the Plateau–Rayleigh (P–R) instabilities in liquids. The experimentally observed P–R instability of soft elastic filaments has been recently investigated via numerical and theoretical approaches. However, these contributions focus on the incompressible limit and preclude the nonlinear Poisson’s ratio effects in materials, for example, compressible hydrogels with Poisson’s ratios that can go as low as 0.1. Moreover, most of the research on the solid P–R instability elaborate on the onset, ignoring the post-bifurcation regime. Here we show that compressibility matters and the form of the assumed compressible strain energy density has a significant effect on the onset and the post-bifurcation behavior of elastic P–R instability. For example, the P–R instability can be entirely suppressed depending on the form of the free energy density and Poisson’s ratio. To this end, we employ a robust and variational elastocapillary formulation and its computer implementation using surface-enriched isogeometric finite elements at finite strains. We use an arclength solver to illustrate both stable-unstable amplitude growth and bifurcation points in the entire equilibrium path. Stability maps are drawn with distinct stable-unstable regions over various shear moduli, surface tensions, fiber radii, and applied stretches for cases ranging from quasi-compressible to fully compressible. The presented elastocapillary model proves to be useful in quantifying the surface and bulk energies in competition at finite strains and expected to help improve mechanical characterization of soft materials with at least one dimension that is on the orders of the elastocapillary lengthscale lsolid∼O(nm – mm).

Path Generation for Flexible Flank Polishing on Freeform Surfaces With Uniform Over-Cuts

One of the bottlenecks in flexible flank polishing is the non-uniform over-cuts problem caused by the difficulties of the polishing tool to conform to variable curvatures of the freeform surface along the polishing path. Consequently, it will significantly reduce the quality of finished surfaces and the service life of polishing tools. To solve the problem, a novel path generation method is proposed in this article, which not only gets the uniform over-cut at a single cutter location, but also keeps its uniformity over an entire polishing path. First, a tool orientation model is built on the freeform surface by analyzing the process of flexible flank polishing. Then, a novel indicator of over-cut uniformity is proposed with the developed Dupin indicatrix, and the tool orientation is determined by maximizing the indicator. Next, based on Taylor expansion, a polishing path generation method is presented with the consideration of over-cut uniformity. Finally, the proposed method is verified and analyzed relative to a comparison method by both virtual simulations and physical experiments. These results present a good consistency with each other and together provide strong support for the correctness, feasibility, and efficiency of the proposed method, which further contributes to surface quality and polishing tools service life.

The Effect of Collectivization on the Fate of Russia in the 20th Century

This article discusses the phenomenon of collectivization and concludes that it is the most important event in the history of Russia in the twentieth century, which radically changed its agrarian system and had a huge impact on the subsequent development of the country. It is pointed out that collectivization cannot be understood without comprehending the entire historical path of Russian modernization. This article analyzes the Bukharin alternative to Stalinist collectivization, characterizes the historical significance of the creation of the collective farm system in the Soviet Union, and considers its impact on the economy and the mentality of the Soviet peasantry.

Potentials of implementing liquid-separation to a transient wrap-around microchannel condenser coil within heat pump water heater

Dynamic characteristics of wrap-around microchannel condenser coil are essential to heat pump water heater (HPWH) during heating-up transient. In this paper, effectiveness of applying liquid-separation technology to the wrap-around microchannel condenser coil is discovered. A mathematical model adopting “quasi-steady-state” and “segment-tube-path” approaches is established for the water tank and microchannel condenser coil. Its predictions on both liquid-separation microchannel condenser coil (LMC) and conventional microchannel condenser coil (CMC) are in good agreements with experimental data. Results show that simply employing separators in the condenser coil (LMC-I) does not bring improvement. The average heat transfer coefficient of LMC-I is enhanced by 10.34% and 5.75% at the entrances of the second and third paths compared to that of CMC, respectively, whereas it is degraded at the outlets of the second and third paths as well as in the entire fourth path. However, LMC-I achieves a significant pressure drop reduction by 34.48%. Thereafter, LMC-II is screened from 963 candidates of path arrangements, and has better performances in terms of higher heat capacity and shorter heating time than both CMC and LMC-I. Its average proportion of 51.83% of two-phase area to the total area is also superior to both CMC and LMC-I.

Technology for programming contour milling on a CNC machine

This paper reports a new technology for designing control programs for contour milling on CNC machines. The technology enables stabilization of the cutting process along the entire contour at the optimal level by controlling the feed, which ensures an increase in productivity when meeting the requirements for restrictions. Moreover, the effectiveness of using the technology improves with an increase in the complexity of the contour by changing the curvature of the surface. A mathematical model has been built for the interaction between the cutter and workpiece in the cutting zone when machining contours with variable curvature, which makes it possible to determine the main characteristic of the cutting process – the rate of cutting the allowance. The technology involves the use of a control program in G codes designed in any CAM system. At the first stage, a shape-formation trajectory in the form of a two-dimensional digital array is derived from the program. At the second stage, the cutter workpiece engagement in the cutting area is modeled simulated while determining the main characteristic of the cutting process – an analog of the material removal rate. And at the final stage, the simulation results are used to design a new control program, also in G-codes, with a new recorded law to control the feed, which enables the stabilization of the cutting process along the entire milling path. The software for the new technology has been developed, which automatically converts the preset control program in G-codes into a two-dimensional digital array, simulates the milling process, and designs a new control program in G-codes based on its results. The results of the experimental study into the milling of the preset contour using the developed simulation program showed an increase in productivity by 1.7 times compared to the original control program, designed in a conventional CAM system

A Vision-Based Approach for Autonomous Motion in Cluttered Environments

In order to complete various tasks automatically, robots need to have onboard sensors to gain the ability to move autonomously in complex environments. Here, we propose a combined strategy to achieve the real-time, safe, and smooth autonomous motion of robots in complex environments. The strategy consists of the building of an occupancy grid map of the environment in real time via the binocular system, followed by planning a smooth and safe path based on our proposed new motion-planning algorithm. The binocular system, which is small in size and lightweight, can provide reliable robot position, attitude, and obstacle information, enabling the establishment of an occupancy grid map in real time. Our proposed new algorithm can generate a high-quality path by using the gradient information of the ESDF (Euclidean Signed Distance Functions) value to adjust the waypoints. Compared with the reported motion-planning algorithm, our proposed algorithm possesses two advantages: (i) ensuring the security of the entire path, rather than that of the waypoints; and (ii) presenting a fast calculation method for the ESDF value of the path points, one which avoids the time-consuming construction of the ESDF map of the environment. Experimental and simulation results demonstrate that the proposed method can realize the safe and smooth autonomous motion of the robot in a complex environment in real time. Therefore, our proposed approach shows great potential in the application of robotic autonomous motion tasks.

The Impact of Blockchain Technology and The Internet of Things on the Agile and Sustainable Supply Chain

In addition to being a revolutionary technology for all industries, the Internet of Things; has also shown its potential in processes such as supply chain. With the advancement of technology and the emergence of the new era, the challenges of the traditional supply chain that follows a path from top to bottom (suppliers of raw materials to final consumers) are revealed. Also, due to environmental issues and the increasing speed of the changes in the needs of customers in various industries, including the retail industry, which has undergone many changes with the emergence of innovation, the entire path of the supply chain requires the implementation of strategies such as agile and green supply chains and achieving smartness. Therefore, emerging technologies such as The Internet of Things play a significant role in the agility and greenness of the entire retail supply chain. The presence of blockchain technology with decentralized data archiving in supply chain processes based on the Internet of Things guarantees the security of big data and helps in optimal data performance. This helps the agility of supply chain processes. In this chapter, dimensions, components, and key indicators effective in the implementation of an agile smart supply chain based on transformative technologies are examined.

Nanostructured Titanium Implant Surface Facilitating Osseointegration from Protein Adsorption to Osteogenesis: The Example of TiO2 NTAs.

Titanium implants have been widely applied in dentistry and orthopedics due to their biocompatibility and resistance to mechanical fatigue. TiO2 nanotube arrays (TiO2 NTAs) on titanium implant surfaces have exhibited excellent biocompatibility, bioactivity, and adjustability, which can significantly promote osseointegration and participate in its entire path. In this review, to give a comprehensive understanding of the osseointegration process, four stages have been divided according to pivotal biological processes, including protein adsorption, inflammatory cell adhesion/inflammatory response, additional relevant cell adhesion and angiogenesis/osteogenesis. The impact of TiO2 NTAs on osseointegration is clarified in detail from the four stages. The nanotubular layer can manipulate the quantity, the species and the conformation of adsorbed protein. For inflammatory cells adhesion and inflammatory response, TiO2 NTAs improve macrophage adhesion on the surface and induce M2-polarization. TiO2 NTAs also facilitate the repairment-related cells adhesion and filopodia formation for additional relevant cells adhesion. In the angiogenesis and osteogenesis stage, TiO2 NTAs show the ability to induce osteogenic differentiation and the potential for blood vessel formation. In the end, we propose the multi-dimensional regulation of TiO2 NTAs on titanium implants to achieve highly efficient manipulation of osseointegration, which may provide views on the rational design and development of titanium implants.

On the Development of a High-Performance Millimeter-Wave Fully-Integrated BiCMOS FDD T/R Front-End Module for 5G Wireless Systems

A new millimeter-wave (mm-wave) fully-integrated 0.18-<inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> BiCMOS frequency division duplex (FDD) transmit&#x2013;receive (T/R) front-end module with internal power amplifier (PA) and low noise amplifier (LNA) is reported. It employs an active circuit to cancel the transmitter (TX) signal leaking into the receiver (RX). The T/R module provides 43.6 dB isolation between the PA output and LNA input at 29 GHz and 9.5 dB average noise figure (NF) over 27&#x2013;29 GHz on the entire RX path. At 29 GHz, the T/R module has 13.8 and 10.6 dB gain on the RX and TX path, respectively. A design methodology is also presented for maximum isolation and optimum NF. It occupies a small area of 2 mm².