Dummy Symbols Research Articles

PAPR Reduction in MIMO-OFDM via Power Efficient Transmit Waveform Shaping

In this paper we revisit the long standing problem of peak-to-average power ratio minimization in MIMO-OFDM systems, with a new angle of approach on a well-known scheme. Utilizing the principles of tone reservation, we place dummy symbols, i.e., complex coefficients, on unused space-frequency resources with the aim to jointly minimize the transmit signal PAPR and the self-power consumption of the dummy symbols. This joint minimization is solved using three different proposed algorithms exhibiting varying degrees of computational complexity and PAPR reduction performance. Our proposed framework utilizes the strict PAPR expression, i.e., we take into account the average transmit power of the antenna, to simultaneously reduce the PAPR on all antennas while keeping the self-power consumption of the scheme minimal. Our simulation results show that this optimization objective provides better worst-case PAPR reduction and dummy symbol power consumption performance compared to the peak power minimization objective widely utilized in the tone reservation literature. Finally, we propose a novel take on a well-known block-diagonalization algorithm by exploiting knowledge on dummy symbol allocations, resulting in high-gain data streams in downlink transmission.

Facile Solutions to the Problems Associated with Chemical Information and Mathematical Symbolism While Using Machine Translation Tools.

Advances in computer-aided translation technology have made tremendous progress in accuracy in the past few years. Chemical Abstracts Service of the American Chemical Society summarizes scientific works from more than 50 languages and allows the users to search papers in nine selected languages. Currently, only the abstracts are rendered into English by human experts or by machine translation because full text translation of millions of articles is beyond the human capacity today. An English translation of a research paper, scientific book, or patent is often required for research, data mining, and for historical purposes from various foreign languages. Many fundamental papers in chemistry, quantum chemistry, physics, and mathematics contain a significant number of chemical or mathematical equations. One of the major known problems in machine translation of such symbolically dense texts is incorrect or meaningless output. This article describes how to optimize the existing machine translation tools to read foreign language papers embedded with chemical/mathematical equations. German and French languages have been selected for illustrative purposes for English translation. Direct upload of text with extensive symbolism is possible with certain services, but this also occasionally produces erroneous rendition into English. A facile solution to the associated problems with embedded equations and mathematical formulas is replacing the equations and notations with "dummy" variables. The placeholder or dummy symbols can be removed after translation, and the original equations are substituted again. This approach, which can be automated in future, relies on the idea that chemical formulas and mathematical notations are universal. Following the guidelines in the article, excellent translations can be produced from a text having interspersed equations and chemical symbols.

Deep Neural Network for Automatic Image Recognition of Engineering Diagrams

Piping and instrument diagrams (P&IDs) are a key component of the process industry; they contain information about the plant, including the instruments, lines, valves, and control logic. However, the complexity of these diagrams makes it difficult to extract the information automatically. In this study, we implement an object-detection method to recognize graphical symbols in P&IDs. The framework consists of three parts—region proposal, data annotation, and classification. Sequential image processing is applied as the region proposal step for P&IDs. After getting the proposed regions, the unsupervised learning methods, k-means, and deep adaptive clustering are implemented to decompose the detected dummy symbols and assign negative classes for them. By training a convolutional network, it becomes possible to classify the proposed regions and extract the symbolic information. The results indicate that the proposed framework delivers a superior symbol-recognition performance through dummy detection.

Transform Methods for the Reduction of the Peak to Average Power Ratio for the OFDM Signal

The paper presents multitransform OFDM-OP system for an effective PAPR (peak to average power ratio) reduction that has a reasonable computational requirement, does not introduce any distortion, needs relatively insignificant decrease in the bandwidth efficiency, and provides a PAPR very close to that for the single carrier modulation systems thus effectively eliminating any PAPR penalty incurred by the multicarrier OFDM system. The PAPR system consists of a bank of multiple orthonormal transforms and a minimum PAPR evaluation unit for finding the optimum transform index. The paper also presents a hybrid OFDM-OP-DSI system comprised of the multiple transforms and a novel dummy symbol insertion. The PAPR reduction performance of the presented systems is compared with those of the various other transform techniques of the literature. Various simulations on the presented systems show that these can achieve a PAPR that is very close to that of a single carrier system for QAM modulation with the order of modulation selected to be 16, 64, and 256.

Fictionalist Nominalism and Applied Mathematics

For at least century, mathematics has been fertile source of arguments against nominalism. Among such arguments, arguments that are based on applied mathematics have at least one important advantage over arguments based on pure mathematics. Nominalists, upon being convinced that Banach-Tarski Theorem-which has no conceivable application to physical world-was inconsistent with nominalism, might well be willing to say, So much worse for Banach-Tarski Theorem. But few nominalists would be willing simply to toss NonLinear Partial Differential Equations for Scientists and Engineers (by Professor Lokenath Debnath; a very hard act to follow, according to one reviewer) into fire. It would be heroic nominalist indeed who was willing to dismiss that book-or any of thousands of other books of similar nature-with words, Does it contain any abstract reasoning concerning quantity or number? Yes. Commit it then to flames: for it can contain nothing but sophistry and illusion.In my view, arguments from applied mathematics are particularly difficult for fictionalist nominalists to deal with.1 In section 1, I will present an argument based on applied mathematics against nominalism simpliciter. (The argument is coextensive with section. Although I in fact accept argument, Section 1 is no more than presentation or statement of argument, and none of declarative sentences it contains should be taken to be an assertion of author's.) In section 2, I will present modification of argument of section 1 that is directed specifically against fictionalist nominalism. In section 3,1 will consider reply to argument of section 2 that is based on common fictionalist contention that the mathematical fiction can be shown to be conservative extension of nominalistically acceptable discourse.1. An Argument for Rejecting NominalismLet us consider simple problem whose solution requires an application of mathematics to physical world.2 We suppose that Alice wishes to find number of cans (cylindrical cans, each with dimensions of sample can she has in her possession) of Sherwin-Williams Porch and Floor Enamel (her favorite floor paint) needed to paint floor of Mary Lou Beasley Reading Room-a rectangular room, length of whose sides she is in position to measure-given that one needs 0.02 cubic units of this paint to cover surface whose area is 100 square units. (Units are units of linear measure: meters, centimeters, nanometers, inches, leagues, parsecs.) This simple problem, as befits simple problem, is easily solved. To solve it, Alice need only apply following general principle to floor of Beasley Room:1.1 The rectangular-surface/paint-can numerical requirement principleNRP For any rectangular surface R and any numbers3, x, y, z, and w: if x and y lengths of two adjacent sides of R in Ls, and if z measures height of can of paint4 in Ls and w measures its diameter in Ls, then number of cans of paint that are needed to paint R is5 0.00025 (xy/w2z).Note that NRP has been presented in form of schema. Instances of this schema are obtained by replacing each occurrence therein of dummy symbol 'Ls' with (the same) plural expression signifying unit of linear measure (ULM). Examples of ULMs are: 'meter', 'inch', 'league', 'nanometer', 'terrestrial polar diameter', 'cubit', and 'astronomical unit'. Thus, one instance of NRP will contain phrase '. . . ifx and y lengths of two adjacent sides of R in meters, and if z measures height of can of paint in meters . . ,'.6To accept or assent to NRP (or any schema) is to accept or assent to ('to commit oneself to accepting'? 'to be prepared to assent to'?) all its instances.Alice need only apply NRP to case at hand-yes. But in order to apply NRP to case at hand, she will first have to know of two numbers that they lengths of two adjacent sides of floor of Beasley Room in meters (or in nanometers or in parsecs . …

Combined channel estimation and PAPR reduction technique for MIMO–OFDM systems with null subcarriers

In this article, we address the challenges regarding the provision of channel state information as well as reducing peak-to-average power ratio (PAPR) of a multiple input multiple output orthogonal frequency multiplexing (MIMO–OFDM) system. The mean squared error (MSE) of the channel estimate is adopted as the optimization criterion to design pilot symbols for channel estimation in MIMO–OFDM systems with null subcarriers. We design the placement and power distribution to the pilot symbols for multiple transmit antennas to minimize the MSE of the least square (LS) channel estimates. To reduce interference of the pilot symbols transmitted from different antennas, an algorithm to guarantee that pilot symbols are disjoint from any other transmitter pilot set is proposed. To efficiently reduce the PAPR of the MIMO–OFDM signals, a method that mixes dummy symbols and phase information of the pilot symbols is presented. Simulation results based on IEEE 802.16e are presented to illustrate the superior performance of our proposed channel estimation method over the existing standard and the partially equi-spaced pilot symbols. We also demonstrate that, by mixing the dummy symbols and phase information of the pilot symbols, the PAPR of the MIMO–OFDM signals can significantly be reduced.

Secure Arithmetic Coding with Error Detection Capability

Recently, arithmetic coding has attracted the attention of many scholars because of its high compression capability. Accordingly, this paper proposed a Joint Source-Cryptographic-Channel Coding (JSCC) based on Arithmetic Coding (AC). For this purpose, embedded error detection arithmetic coding, which is known as continuous error detection (CED), is used. In our proposed method, a random length of forbidden symbol which is produced with a key is used in each recursion. The dummy symbol is divided into two dummy symbols with a key and then is placed in random positions in order to provide security. Finally, in addition to producing secure codes, the suggested method reduced the added redundancy to half of the total redundancy added by CED. It has less complexity than cascades source, channel coding, and encryption while its key space in comparison to other joint methods has enlarged. Moreover, the coder provides a flexible switch between a standard compression model and a joint model.

A Flexible Peak-To-Average Power Ratio Reduction Scheme for OFDM Systems by the Adaptive Projected Subgradient Method

One of the main issues of the orthogonal frequency-division multiplexing (OFDM) modulation is the high peak-to-average power ratio (PAPR) of the transmitted signal, which adversely affects the complexity of power amplifiers. In this paper, we consider transmitters that reduce the PAPR by slightly disturbing the symbols in carriers used to transmit information and by sending dummy symbols-i.e., symbols not conveying information-in unused carriers. The optimal choice of the data and dummy symbols is determined by the solution of a convex optimization problem. To reduce the PAPR with low complexity, we apply a modified version of the adaptive projected subgradient method to a sequence of convex cost functions closely related to the original optimization problem. The resulting algorithm achieves near-optimal PAPR in practical scenarios, generalizes existing algorithms based on Polyak's method, and can easily handle multiple constraints.

A MODERN ENGLISH MODEL OF ‘SIMPLE’ GRAMMAR FOR NATURAL LANGUAGES

O. AbstractA natural language is presented as a triple, (W, Nom, Sbst), where W is the set of non‐lexical (primitive) sentences, each having the unquantified atomic form of the sentence in predicate logic with its arguments (constituents) denoted by dummy symbols and Sbst is the operation of substitution, which transforms primitive sentences into ordinary lexical sentences by replacing the dummy symbols with nominals, the output of Nom, nominalization, which is an operation applying to both primitive and lexical sentences as input. The sentence, primitive or lexical, has no molecular complexity, as so‐called compound and complex sentences using various conjunctions are shown to be simple sentences with the atomic form. The theory is illustrated by a complete ‘simple’ grammar of Modern English.