String Length Research Articles

On the dynamics of drilling

A multi-parameter approach for analysing drilling dynamics is developed. It is oriented to better understanding peculiarities of the process and optimising existing formulations. The procedure is specified for bending vibrations of a rotating elastic beam pre-stressed simultaneously by an axial compressive force and torque. The appropriately normalized ratio of the bending stiffness to the axial force magnitude is assumed to be small. Two other independent dimensionless parameters correspond to the vibration frequency and the relation between force and torque magnitudes. A classification, similar to that in thin shell theory, is established for free bending vibrations. The associated shortened equations are derived. The asymptotic results are validated by comparison with the dispersion curves calculated from the original full equation of motion. An example of a boundary-value problem for a drill string of a finite length is also presented.

Reduction of the number of faults caused by lightning for transmission line

In this paper, author proposed an algorithm to determine method which is used to reduce the fault number caused by lightning on a transmission line. The algorithm is developed based on three methods including increase in the insulator string length, surge arrester installation, and surge arrester installation in combination with increase in the insulator string length. The output of algorithm is the proposed method which makes the number of faults caused by lightning satisfy the requirement and its investment is the cheapest in them. Based on this algorithm, the reasonable method (the number of tower positions needing to improve) to reduce the number of lightning caused faults of the transmission line can determine if we know the ratio of the required number lightning caused faults to the current value. This algorithm is applied to a transmission line to propose an improving method so that the fault number satisfies the requirement. This algorithm is implemented to a 220kV transmission line. The calculation results show the reasonable method and it also indicates in detail which towers should install surge arrester, which towers should increase the insulator string length.

Surface and Curve Languages

In the area of combinatorial studies of string languages under formal grammars, the concept of Generalized Parikh Vector (GPV) gives the positions of symbols in linear strings. It has been proved that GPVs of the strings of the same length lie on a hyper plane. The studies on GPV of strings over a binary alphabet gave rise to the concept of line languages. The concept has been extended to surface languages in this paper.

Feasibly constructive proofs of succinct weak circuit lower bounds

We ask for feasibly constructive proofs of known circuit lower bounds for explicit functions on bit strings of length n. In 1995 Razborov showed that many can be proved in PV1, a bounded arithmetic formalizing polynomial time reasoning. He formalized circuit lower bound statements for small n of doubly logarithmic order. It is open whether PV1 proves known lower bounds in succinct formalizations for n of logarithmic order. We give such proofs in APC1, an extension of PV1 formalizing probabilistic polynomial time reasoning: for parity and AC0, for mod q and AC0[p] (only for n slightly smaller than logarithmic), and for k-clique and monotone circuits. We also formalize Razborov and Rudich's natural proof barrier.We ask for short propositional proofs of circuit lower bounds expressed succinctly by propositional formulas of size nO(1) or at least much smaller than the 2O(n) size of the common “truth table” formula. We discuss two such expressions: one via feasible functions witnessing errors of circuits, and one via the anticheckers of Lipton and Young 1994. Our APC1 formalizations yield conditional upper bounds for the succinct formulas obtained by witnessing: we get short Extended Frege proofs from general circuit lower bounds expressed by the common “truth-table” formulas. We also show how to construct in quasipolynomial time propositional proofs of quasipolynomial size tautologies expressing AC0[p] quasipolynomial size lower bounds; these proofs are in Jeřábek's system WF.

The r-Hamming gap and distance-gap-preserving mappings from binary vectors to permutations

The well known Hamming distance between a pair of permutations (or strings) of the same length is simply the number of pairs of different digits in these permutations. It has been an interesting topic of research to find mappings from the binary vectors to permutations of the same length such that the Hamming distance is preserved or increased. As a natural variation we introduce the Hamming gap of radius r between two permutations, which is, in a way, equivalent to the number of digits where the corresponding pair of entries differ by at least r. This is called the r-Hamming gap. We first discuss the properties of this new concept. We then show mappings from binary vectors to permutations such that the images of a pair of binary vectors (at Hamming distance d) have r-Hamming gap at least d. We also show the generalization of our findings to permutations on Zn (where n ≡ 0) instead of [n].

Branching Measures and Nearly Acyclic NFAs

To get a more comprehensive understanding of the amount of branching in computations of a nondeterministic finite automaton (NFA), we introduce and study the string path width and depth path width measures. For a given NFA, the string path width on a string [Formula: see text] counts the number of all complete computations on [Formula: see text], and the depth path width on an integer [Formula: see text] counts the number of complete computations on all strings of length [Formula: see text]. We give an algorithm to decide the finiteness of the depth path width of an NFA. Deciding finiteness of string path width can be reduced to the corresponding question on ambiguity. An NFA is nearly acyclic if any computation can pass through at most one cycle. The class of nearly acyclic NFAs consists of exactly all NFAs with finite depth path width. Using this characterization we show that the finite depth path width of an [Formula: see text]-state NFA over a [Formula: see text]-letter alphabet is at most [Formula: see text] and that this bound is tight. The nearly acyclic NFAs recognize exactly the class of constant density regular languages.

Stringy effects and the role of the singularity in holographic complexity

There has been considerable recent interest in holographic complexity. The two leading conjectures on this subject hold that the quantum complexity of the boundary thermofield double state should be dual to either the volume of the Einstein-Rosen bridge connecting the two sides (CV conjecture) or to the action of the Wheeler-de-Witt patch of the bulk spacetime (CA conjecture). Although these conjectures are frequently studied in the context of pure Einstein gravity, from the perspective of string theory it is also natural to consider models of gravity in which general relativity is perturbed by higher powers of the Riemann tensor, suppressed by powers of the string length; in a holographic context, these corrections are dual to corrections in inverse powers of the ’t Hooft coupling. In this paper, we investigate the CV and CA conjectures in two stringy models of higher-curvature gravity. We find that the CV complexification rate remains well-behaved, but conversely that these corrections induce new divergences in the CA complexification rate that are absent in pure Einstein gravity. These divergences are intrinsically linked to the singularity, and appear to be generic in higher curvature theories. To the best of our knowledge, infinities originating at the singularity have not yet been observed elsewhere in the literature. We argue that these divergences imply that, in the CA picture, the complexification rate of the boundary theory is a nonanalytic function of the ’t Hooft coupling.

Meta-Feature Classification to Explore Automatic Detection of Malware Using Segmentation Method

Paper Anti-malware software producers are persistently tested to recognize and counter new malware as it is discharged into nature. An emotional increment in malware generation as of late has rendered the ordinary technique for physically deciding a mark for each new malware test unsound. This paper introduces a versatile, mechanized methodology for identifying and arranging malware by utilizing design acknowledgment calculations and measurable techniques at different phases of the malware examination life cycle with Meta highlights. By utilizing a regular fragment examination, Mal-ID can dispose of malware parts that start from kindhearted code. What's more, Mal-ID uses another sort of highlight, named Meta-include, to more readily catch the properties of the dissected portions. In this paper, we introduce Ensemble Classifier technique to handle malware uncovering based on meta features. Our system consolidates the static highlights of capacity length and printable string data separated from malware tests into a solitary test which gives order results superior to those accomplished by utilizing either include independently. In our testing, we information includes data from near 1400 unloaded malware tests to various diverse grouping calculations. Utilizing k-overlap cross approval on the malware, which incorporates Trojans and infections, alongside 151 clean records, we accomplish a general characterization exactness of over 98%.

The pseudofossil Horodyskia: Flocs and flakes on microbial mats in a shallow Mesoproterozoic sea (Appekunny Formation, Belt Supergroup, western North America)

Horodyskia moniliformis Yochelson and Fedonkin (2000) is found abundantly in its type area, the lower Appekunny Formation (Belt Supergroup; ca. 1.45 Ga) of northwestern Montana and adjacent southwestern Alberta. It has a distinct curving to meandering string-of-beads appearance on bedding planes of thin-bedded, laminated argillaceous siltstone, and has been regarded by some as one of the oldest eukaryotic organisms in the fossil record. The beads are disc-shaped to lenticular, ~1–5 mm in diameter, circular to elliptical to polygonal in outline, and composed of variably silty clay. They are interpreted as mud flocs and small intraclasts. The beads in individual specimens are fairly uniform in size and spacing, but string length varies from about one to 15 cm depending in part on bead size. The radius of curvature varies from tight to open, but strings never form loops. Isolated beads are also present and smaller ones become indistinguishable from pustules which, along with mud-cored wrinkles and blisters, are associated on many bedding surfaces. These are regarded as evidence for a benthic microbial mat with variable topography ranging from crudely linear or stellate ridges to small domes and pinnacles. Rather than representing a semi-infaunal colonial eukaryote, fungal bladders or macroalgae, Horodyskia is here interpreted to be large mud particles that were trapped on small protrusions of the microbial mat probably consisting of filament tufts. Commonly, the tufts were oriented in rows of similar-sized and generally evenly spaced elevations and these bound suspended flocs and flakes of a more or less uniform size, resulting in the features that appear organized as strings-of-beads. Horodyskia is therefore considered to be a microbially-induced sedimentary structure specific to a muddy, relatively low-energy, subtidal marine setting with just the right combination of sediment type and depositional factors.

Security aspects of the Cayley hash function using discrete heisenberg group

We execute the average running time of the various binary strings of different length and evaluate the other useful characteristics of a hash function which is to be Pseudo-Randomness of a hash function,which can assigned Uniformly over the range [0,p) to reduce the chance of occurring collisions. We also verify the security properties of the hash function using different attacks.

Approximate pattern matching on elastic-degenerate text

An elastic-degenerate string is a sequence of n sets of strings of total length N. It has been introduced to represent a multiple alignment of several closely-related sequences (e.g., pan-genome) compactly. In this representation, substrings of these sequences that match exactly are collapsed, while in positions where the sequences differ, all possible variants observed at that location are listed. The natural problem that arises is finding all matches of a deterministic pattern of length m in an elastic-degenerate text. There exists a non-combinatorial O(nm1.381+N)-time algorithm to solve this problem on-line [1]. In this paper, we study the same problem under the edit distance model and present an O(k2mG+kN)-time and O(m)-space algorithm, where G is the total number of strings in the elastic-degenerate text and k is the maximum edit distance allowed. We also present a simple O(kmG+kN)-time and O(m)-space algorithm for solving the problem under Hamming distance.

Influence of Standard Lightning Impulse Front Time Tolerances on the Flashover Voltage of Suspension Insulators

For high voltage impulse testing, a standard lightning impulse is defined in IEEE Std. 4 and IEC 60060-1 as a double exponential waveform having a front time T1 = 1.2 μs ± 30% and time to half-value T2 = 50 μs ± 20%. It has been noticed that for a given specimen, it is possible to successfully pass a flashover test at one end of the T1 tolerance range while failing the same test at the opposite end of the tolerance spectrum. Consequently, a systematic approach was adopted to investigate this observation. Up-and-down tests were performed to define the disruptive discharge voltage (critical flashover voltage CFO, U50) for 1, 5, 10, and 15 unit glass insulator strings standard lightning impulses using the minimum acceptance front time value (T1 ≈ 0.84 μs). Tests were repeated using the maximum tolerance value (T1 ≈ 1.56 μs) to investigate the degree of divergence in the flashover value. Particular attention is given to the steepness (voltage-time characteristics) of the applied impulse to consider if tolerance criteria amendment is merited in a future standard revision. As the steepness impact is more renowned in non-uniform geometries, field homogeneity as a function of string length is also incorporated into the analysis.

On Hamming index generated by adjacency matrix of graphs

Let G be a finite simple graph and A be the adjacency matrix of G. Then each row of A is a bit string of finite length. Hamming distance between any two rows of A is defined to be the number of positions with different digit. For any two vertices vi and vj in graph G we define Hamming distance, generated the adjacency matrix A, between vi and vj as the Hamming distance between rows of A corresponding to the vertices vi and vj. The Hamming index of the graph G is the sum of Hamming distances over all distinct pairs of vertices vi and vj in G. This paper discuss Hamming index of finite simple graphs. We present a formula for Hamming index of graphs in terms of known parameters of the graph namely the number of vertices, the number of edges and the degree of each vertex. We then apply the formula to determine the Hamming index for some graph operations.

Hamming Index for Several Graph Classes Produced by an Side-Node Incidence Matrix

For example G(V,E) becomes graph on p nodes and q sides and B’(G) called being side-node incidence matrix from G. Every side e of G can be labeled using a binary digit string of length n from the row of B’(G) which corresponds to the side e, denoted by s(e). The Hamming distance between the strings s(e) and s(f) of length n is defined to be the number of positions of s(e) and s(f) with different digit. Hamming index from a graph is the number of Hamming distances between all pairs of strings. In this research, author discuss the Hamming index of graphs produced by an side-node incidence matrix, particularly windmill graph and snake graphs.

A Successor Rule Framework for Constructing $k$ -Ary de Bruijn Sequences and Universal Cycles

We present a simple framework for constructing $k$ -ary de Bruijn sequences, and more generally, universal cycles, via successor rules. The framework is based on the often used method of joining disjoint cycles. It generalizes several previously known de Bruijn sequence constructions based on the pure cycling register and is applied to derive a new construction that is perhaps the simplest of all successors. Furthermore, it generalizes an algorithm to construct binary de Bruijn sequences based on any arbitrary nonsingular feedback function. The framework is applied to derive and prove the correctness of successors to efficiently construct 1) universal cycles for $k$ -ary strings of length $n$ whose weight is bounded by some $w$ and 2) universal cycles for permutations. It has also been subsequently applied to find the first universal cycle constructions for weak orders.

Optimal bounds for computing α-gapped repeats

Following (Kolpakov et al., 2013; Gawrychowski and Manea, 2015), we continue the study of α-gapped repeats in strings, defined as factors of the form uvu with |uv|=|u|+|v|≤α|u|. Our main result is the O(αn) bound on the number of maximal α-gapped repeats in a string of length n, previously proved to be O(α2n) in (Kolpakov et al., 2013). For a closely related notion of maximal δ-subrepetition (maximal factors of exponent between 1+δ and 2), our result implies the O(n/δ) bound on their number, which improves the bound of (Kolpakov et al., 2010) by a log⁡n factor.We also prove an algorithmic time bound O(αn+S) (S size of the output) for computing all maximal α-gapped repeats. Our solution, inspired by (Gawrychowski and Manea, 2015), is different from the recently published proof by (Tanimura et al., 2015) of the same bound. Together with our bound on S, this implies an O(αn)-time algorithm for computing all maximal α-gapped repeats.

Pertumbuhan Rumput Laut Kappaphycus alvarezii Yang Dikultur Menggunakan Dua Jenis Tali Ris Dengan Kondisi Berbeda

The study aimed to determine the growth of seaweed Kappaphycus alvarezii cultured using different type of rope ris with different conditions. The study was conducted over 64 days, starting on September 1 to November 3, 2014 Village Jaya Karsa, North Minahasa Regency, North Sulawesi. The experiment was designed according to 2x3 factorial experiment in a completely randomized design (CRD). Two factors were tested, namely rope ris type and conditions. Factors ris types strap consisted of two type: Monofilament nylon and Multifilament PE. Factor conditions of ris rope consisted of three levels, namely: new, used cleaned, and the former was not cleaned, so there were 6 treatments. Experiment container was floating longlines. One unit consisted of 3 longline trial. Length per longline 28.80 m, 18 pieces of string length of rope ris 1.6 m each strap was 7 point planting, planting the overall number of points 378 points planting. K. alvarezii seaweed seedlings obtained from Jaya Karsa farmers. Weighing was done 4 times, weighing early, 1 week, 2 weeks, and at the end of week 3, using a digital scale with a precision of 1 g. Accretion weight was calculated to be the absolute growth rate (g) and daily growth rate (%). The results showed that the absolute growth and the daily growth of seaweed K. alvarezii not significantly influenced by different type and condition of the rope ris. Keywords : Kappaphycus alvarezii, long line, Multifilament PE, Monofilament nylon.

Quantum interference enables constant-time quantum information processing.

It is an open question how fast information processing can be performed and whether quantum effects can speed up the best existing solutions. Signal extraction, analysis, and compression in diagnostics, astronomy, chemistry, and broadcasting build on the discrete Fourier transform. It is implemented with the fast Fourier transform (FFT) algorithm that assumes a periodic input of specific lengths, which rarely holds true. A lesser-known transform, the Kravchuk-Fourier (KT), allows one to operate on finite strings of arbitrary length. It is of high demand in digital image processing and computer vision but features a prohibitive runtime. Here, we report a one-step computation of a fractional quantum KT. The quantum d-nary (qudit) architecture we use comprises only one gate and offers processing time independent of the input size. The gate may use a multiphoton Hong-Ou-Mandel effect. Existing quantum technologies may scale it up toward diverse applications.

The geometric properties of an infinitary line and plane languages

Formal grammar is an area of discrete mathematics dealing with syntactic techniques of generation of words and their properties. The concept of Parikh vector (PV) and Generalized Parikh vector (GPV) play important role in the combinatorial properties of words under formal grammars. The concept of Generalized Parikh Vector introduced by Siromoney et al. gives the positions of symbols in linear strings. It has been proved that GPVs of the strings of the same length lie on a hyper plane. As any formal language over binary letters are represented geometrically, the study done in this paper explore geometrical properties of lines induced by corresponding languages. The study is extended over three alphabet set giving rise to plane objects.

Analysis of factors affecting drilling friction and investigation of the friction reduction tool in horizontal wells in Sichuan

Based on field data and the related theories, the effects of drill string length, rotation speed, trajectory, and drilling fluid density on the friction during horizontal well drilling are analyzed in Sichuan. With increasing the length of drill string in the horizontal section, the friction grows. The drill pipe rotates faster and the torque decreases. Large undulation of borehole deviation and the “W” shape of the horizontal section lead to excessive friction. A higher fluid density causes higher torque and drag. Moreover, a friction reduction tool is designed to reduce friction, decrease the wear between the casing and the drill pipe joint, and prevent the differential pressure sticking, which improves the rate of penetration, and the specially designed spiral diversion channels improve the efficiency of borehole cleaning. The field experimental results have shown that the accumulated operational time of the friction reduction tool is more than 130 h and its fatigue life reaches up to 3 × 105 cycles. A plan of improving the tool structure is proposed to reduce the mud balling after the experiment. Finally, the mathematical model of calculating the spacing of the friction reduction tools is established, which provides technical support for investigating the friction in horizontal well drilling.