2D Symbols Research Articles

Secure Encryption and Key Management for OFDM-PON Based on Chaotic Hilbert Motion

We propose a novel security enhancement technique for physical layer secure orthogonal frequency division multiplexed-based passive optical network (OFDM-PON) using chaotic Hilbert motion. By using chaos to construct Hilbert motion, the traversal and the scrambling of two-dimensional (2D) symbol matrix are completed. To enhance the security of the key, we use the key space as an encryption object for the first time, and then we use it as a supporter for key generation and distribution. The Hash value generated by this encryption result is applied as a digital signature to verify the data integrity. An experiment that the signals of 35.29 Gb/s are successfully transmitted over 20 km standard single-mode fiber (SSMF) and a back-to-back (BTB) system. The experimental results show that this scheme provides an effective and widely applicable solution for realizing secure OFDM-PON with high security and low complexity.

Enhanced validation of small-molecule ligands and carbohydrates in the Protein Data Bank

The Worldwide Protein Data Bank (wwPDB) has provided validation reports based on recommendations from community Validation Task Forces for structures in the PDB since 2013. To further enhance validation of small molecules as recommended from the 2016 Ligand Validation Workshop, wwPDB, Global Phasing Ltd., and the Noguchi Institute, recently formed a public/private partnership to incorporate some of their software tools into the wwPDB validation package. Augmented wwPDB validation report features include: two-dimensional (2D) diagrams of small-molecule ligands and carbohydrates, highlighting geometric validation outcomes; 2D topological diagrams of oligosaccharides present in branched entities generated using 2D Symbol Nomenclature for Glycan representation; and views of 3D electron density maps for ligands and carbohydrates, illustrating the goodness-of-fit between the atomic structure and experimental data (X-ray crystallographic structures only). These improvements will impact confidence in ligand conformation and ligand-macromolecular interactions that will aid in understanding biochemical function and contribute to small-molecule drug discovery.

Joint-Mapping-Based Variable Active Antenna Spatial Modulation

Spatial modulation (SM) maps information to both spatial dimensions (active antenna indices) and conventional 2D ${M}$ -ary symbols. The existing SM schemes use fixed number of active antennas in each transmit vector as varying them causes detection ambiguity. Motivated by this, we introduce a new joint-mapping based variable active antenna spatial modulation scheme, which varies the number of active antennas in each transmit vector. It alleviates detection ambiguity by jointly mapping information to the complete 3D constellation consisting of active antenna indices (spatial dimension) and the 2D ${M}$ -ary symbols. This is unlike the existing SM schemes which separately map information to the active antenna indices and the 2D symbols. This idea enables us to i) avoid detection ambiguity; and ii) achieve low bit error rate and comparable maximum likelihood detection complexity as that of existing SM schemes.

Using Eye Tracking to Explore the Guidance and Constancy of Visual Variables in 3D Visualization

An understanding of guidance, which means guiding attention, and constancy, meaning that an area can be perceived for what it is despite environmental changes, of the visual variables related to three-dimensional (3D) symbols is essential to ensure rapid and consistent human perception in 3D visualization. Previous studies have focused on the guidance and constancy of visual variables related to two-dimensional (2D) symbols, but these aspects are not well documented for 3D symbols. In this study, we used eye tracking to analyze the visual guidance from shapes, hues and sizes, and the visual constancy that is related to the shape, color saturation and size of 3D symbols in different locations. Thirty-six subjects (24 females and 12 males) participated in the study. The results indicate that hue and shape provide a high level of visual guidance, whereas guidance from size, a variable that predominantly guides attention in 2D visualization, is much more limited in 3D visualization. Additionally, constancy of shape and saturation are perceived with relatively high accuracy, whereas constancy of size is perceived with only low accuracy. These first empirical studies are intended to pave the way for a more comprehensive user understanding of 3D visualization design.

Gangs of piglets: Welfare and growth of imprinted and guided weaners

Weaning stress accompanied by outburst of aggression is a critical point in pig production as it compromises piglets’ welfare and leads to poor growth rate and health problems. Therefore, a weaning methods to smoothen the lactation–weaning transition are of great importance. In the present study a simple practical approach based on the imprinting phenomenon to improve weaned piglets’ welfare and growth performance was implemented. From birth, piglets were continually exposed to the simple 2D shapes, either a white circle on a black background (WC) or a black cross on a white background (BC). At weaning, piglets were allotted to weaning groups consisting of one WC and one BC litter, whereby test weaning pens, but not the control pens, were virtually divided using WC and BC signage on respective halves of the pen. The approach was tested in low- and high-density weaning groups, i.e. 10 or 20 individuals per pen (120 animals in total). The results revealed better growth performance of the test group (12–17% higher daily gain). On the whole, the number of post-weaning fights was lower in the test group and the majority of fights (62–75%) occurred among WC and BC. As regards the territoriality, piglets post-weaning tendency to remain in the area marked with a familiar sign was in general significant − i.e. more distinct grouping in the test pens (p<0.05), comparing to the control pen. It appears that virtual splitting of weaning pens using simple 2D symbols to which pigs were exposed during lactation may decrease weaning aggression, promote distinct grouping and territorial behaviour, and promote growth performance of weaned piglets under farm conditions, especially in groups with lower stock density.

Image Sensors Meet LEDs

A new class of visible light communication (VLC) systems, namely image sensor (IS) based VLC systems, has emerged. An IS consists of a two-dimensional (2D) array of photodetectors (PDs), and then VLC systems with an IS receiver are capable of exploiting the spatial dimensions invoked for transmitting information. This paper aims for providing a brief survey of topics related to the IS-based VLC, and then provides a matrix representation of how to map a series of one dimensional (1D) symbols onto a set of 2D symbols for efficiently exploit the associate grade of freedom offered by 2D VLC systems. As an example, the matrix representation is applied to the symbol mapping of layered space-time coding (L-STC), which is presented to enlarge the coverage of IS-based VLC that is limited by pixel resolution of ISs.

Binary Large Object-Based Approach for QR Code Detection in Uncontrolled Environments

Quick Response QR barcode detection in nonarbitrary environment is still a challenging task despite many existing applications for finding 2D symbols. The main disadvantage of recent applications for QR code detection is a low performance for rotated and distorted single or multiple symbols in images with variable illumination and presence of noise. In this paper, a particular solution for QR code detection in uncontrolled environments is presented. The proposal consists in recognizing geometrical features of QR code using a binary large object- (BLOB-) based algorithm with subsequent iterative filtering QR symbol position detection patterns that do not require complex processing and training of classifiers frequently used for these purposes. The high precision and speed are achieved by adaptive threshold binarization of integral images. In contrast to well-known scanners, which fail to detect QR code with medium to strong blurring, significant nonuniform illumination, considerable symbol deformations, and noising, the proposed technique provides high recognition rate of 80%–100% with a speed compatible to real-time applications. In particular, speed varies from 200 ms to 800 ms per single or multiple QR code detected simultaneously in images with resolution from 640 × 480 to 4080 × 2720, respectively.

Young children’s ability to use two-dimensional and three-dimensional symbols to show placements of body touches and hidden objects

In two experiments, we investigated 3- to 5-year-old children’s ability to use dolls and human figure drawings as symbols to map body touches. In Experiment 1, stickers were placed on different locations of children’s bodies, and the children were asked to indicate the locations of the stickers using three different symbols: a doll, a human figure drawing, and the adult researcher. Performance on the tasks increased with age, but many 5-year-olds did not attain perfect performance. Surprisingly, younger children made more errors on the two-dimensional (2D) human figure drawing task compared with the three-dimensional (3D) doll and adult tasks. In Experiment 2, we compared children’s ability to use 3D and 2D symbols to indicate body touch as well as to guide their search for a hidden object. We replicated the findings of Experiment 1 for the body touch task; for younger children, 3D symbols were easier to use than 2D symbols. However, the reverse pattern was found for the object locations task, with children showing superior performance using 2D drawings over 3D models. Although children showed developmental improvements in using dolls and drawings to show where they were touched, less than two thirds of the 5-year-olds performed perfectly on the touch tasks. Both developmental and forensic implications of these results are discussed.

Multidimensional Constellations for Power-Efficient and Flexible Optical Networks

Multidimensional constellations and time domain hybrid QAM both realize a non-integer ratio of bits per complex 2D symbol in order to allow for flexibility of spectral efficiency. We compare both approaches in terms of symbol error probability, asymptotic power efficiency, and bit error probability. In order to achieve 400G transmission, as an example for a non-integer ratio, an average number of 3.33 bits per complex 2D symbol was chosen, resulting in a symbol rate of 67.2 GBd including 12% FEC overhead. We show a 0.34-dB gain of multidimensional 16-QAM modulation over a hybrid 8-QAM/16-QAM scheme in terms of asymptotic power efficiency.

Simplification of strip‐wise algorithms applied for two‐dimensional intersymbol interference detection

With the development of the high-speed communication channel or high-capacity storage device, the intersymbol interference (ISI) occurs more frequently in the condensed data. The traditional Bahl – Cocke – Jelineu – Raviv (BCJR) method is capable of solving the two-dimensional (2D) symbol influence problem with extremely high cost. By analysing the complexity in terms of branch, state and path in the 2D trellis-based ISI detection, the authors verify that the system complexity is mainly dominated by the window size. To reduce the detection complexity, the conventional simplifications are applied in the 2D strip-wise ISI detection. In addition, a two-phase strip-wise detection is proposed to achieve a lower complexity than that of the conventional simplifications. In this system, the first detector can be realised by a low-complexity method (like the hard detection or Viterbi algorithm) to provide the mask shrinking with predicted data. After reducing the mask size, the second detector can detect the main portion of ISI by the trellis-based detection (like BCJR algorithm) with a small mask. Under the similar detection performance, the proposed scheme can achieve more than 91.76% saving in the metric computation compared with the 5 × 3-window IRCSDFA (iterative row–column soft-decision feedback algorithm) simplified by the M-algorithm with M = 8.

鋼製器具単品識別によるトレーサビリティシステムの運用評価

We built a traceability system for the management of individual surgical instruments by using 2D symbol and Radio Frequency Identification tags, for the purpose of improving the quality of infection control and risk management, operational improvements and accurate asset management.With this system, we have been able to identify both surgical instruments and patients in a short period of time. It indicates that the traceability system is effective in infection control and risk management. In addition, restoration of discarded data on surgical instruments could be recorded in this system.Therefore, it would be easy to have an accurate inventory and cost data, which may be utilized to make a budget. Consequently, the traceability management will be useful for hospital management. From this time forward, we think that the verification of cost-effectiveness and the standardization of traceability system will be needed.

An investigation of preschoolers' misattributions of the properties of two‐dimensional images: understanding the relationship between a symbol and its referent

AbstractPrevious studies have found that preschoolers are confused about the relationship between two‐dimensional (2D) symbols and their referents. Preschoolers report that 2D images (e.g. televised images and photographs) share some of the characteristics of the objects they are representing. A novel Comparison Task was created to test what might account for these misattributions of the properties of 2D images. Three‐and‐a‐half‐ and four‐and‐a‐half‐year olds made comparisons between items presented in two of three formats simultaneously, i.e. as a real object and as an object appearing on television (TV), as a real object and as a photo of that object, or as an object appearing on TV and in a photo. Presenting the televised object or the photo of the object along with the real object aided performance; children indicated that televised objects and photos of objects no longer shared the properties of the real objects. Children also performed better when presented with two 2D images of the same object (the photo of the object and the televised image of the object). Although dual‐representation might account for these misattributions of the properties of 2D images, because children also performed better when two 2D images of the same object were present, other possibilities such as children using pictures as communicative devices and disregarding the pragmatics of the task should be explored. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Super-quasiorthogonal space-time trellis codes for four transmit antennas with rectangular signal constellations

In this paper, we present the first super-quasiorthogonal space-time trellis codes (SQOSTTCs) for systems with four transmit antennas using various types of rectangular signal constellations to increase the spectral efficiency up to 5 bits/s/Hz. In our wireless communications system, we define an eight-dimensional (8D) signal constellation as Cartesian product of four two-dimensional (2D) rectangular signal sets. The transmission of an 8D point from the first antenna is achieved by transmitting four concatenated 2D points in four consecutive channel uses. The 2D symbols transmitted from the other three antennas are not independent but so chosen as to form, together with the symbols transmitted from the first antenna, the entries of a 4×4 quasiorthogonal transmission matrix. The union of two sets of quasiorthogonal transmission matrices forms a so-called super-quasiorthogonal signal set. With the 4×4 quasiorthogonal transmission matrices, we then label the state transitions of a trellis diagram describing the operation of the encoder. The simulation results of the frame error rate and the bit error rate demonstrate the excellent performance of our proposed SQOSTTCs.

鋼製器械トレーサビリティ向け2次元シンボル読取り装置の特長(&lt;特集&gt;鋼製器械・器具のトレーサビリティの動向)

鋼製器械トレーサビリティ向け2次元シンボル読取り装置の特長(&lt;特集&gt;鋼製器械・器具のトレーサビリティの動向)

Super-orthogonal space-time trellis codes with eight dimensional phase-shift keying signal constellations

We propose a new method of designing super-orthogonal space-time trellis codes (SOSTTCS) by labeling each state transition of the trellis diagram with an ordered pair of 2×2 orthogonal matrices instead of only a single 2×2 orthogonal matrix. An 8D instead of a 4D signal constellation is thus used for modulation and the delay elements of the trellis encoder are 4T instead of 2T, where T is the 2D symbol duration. Therefore, at the receiver, the sequence decoding using Viterbi algorithm requires two times less frequent updating of the branch metrics. We investigate by computer simulation the performance of the new sosttcs compared to sosttcs designed by the known method. The frame error rate (fer) and the bit error rate (ber) simulation results show that the performance of the new sosttcs is practically as good as that of the sosttcs of similar complexity designed along classical lines, with the advantage that the number of arithmetic and logic operations performed by the decoder per time unit is smaller, which is crucial in high data-rate applications.

Super-orthogonal space-time codes with rectangular constellations and two transmit antennas for high data rate wireless communications

We demonstrate super-orthogonal space-time (ST) trellis codes with rectangular signal constellations for wireless communications with a spectral efficiency of 4 bits/s/Hz. Considering a mobile wireless communications system with two transmit antennas, we form a 4D signal constellation as Cartesian product of two 2D rectangular signal sets, a 4D point being transmitted by the first antenna as two concatenated 2D points in two consecutive channel uses. The 2D symbols transmitted by the second antenna are not independent, but so chosen as to form, together with the symbols transmitted by the first antenna, the entries of a 2 times 2 orthogonal matrix. This can be done in four different ways, resulting in four sets of 2 times 2 orthogonal matrices. To obtain a higher data rate, the union of two of them forms a super-orthogonal signal set. With 2 times 2 orthogonal matrices, we then label the state transitions of a trellis diagram describing the operation of the encoder. We perform simulations using a model that takes into account the Doppler effect as well as the effect of spatial antenna correlation at both the base station (BS) and at the mobile station (MS). The frame error rate (FER) and the bit error rate (BER) performance results show an excellent behaviour of our proposed super-orthogonal ST trellis code, which clearly outperforms all known simple ST trellis codes of same spectral efficiency using 16QAM or 16PSK

New super‐orthogonal space‐time trellis codes with 32QAM and two transmit antennas for five bits per signalling interval

AbstractIn this paper, we focus on the design of super‐orthogonal space‐time (ST) trellis codes with a 32‐point quadrature amplitude modulation (QAM) signal constellation, allowing wireless communication with a data rate of 5 bits per signalling interval. Considering a mobile wireless communications system with two transmit antennas, we form a four‐dimensional (4D) signal constellation as a Cartesian product of two 2D rectangular signal sets. The first antenna transmits a 4D point as two concatenated 2D points in two consecutive baud intervals. The 2D symbols transmitted by the second antenna are not independent, but so chosen as to form, together with the symbols transmitted by the first antenna, the entries of a 2 × 2 orthogonal matrix. For a rectangular constellation, as much as four sets of 2 × 2 orthogonal matrices can be built. To obtain a higher data rate, the union of two of them is used to construct a super‐orthogonal signal set. With 2 × 2 orthogonal matrices, we then label the state transitions of a trellis diagram describing the operation of the encoder. For the performance analysis, two different channel models are employed. The first channel model is based on the assumption that the paths between different pairs of transmit–receive antennas are uncorrelated, while the second model takes into account the effect of spatial antenna correlation at both the base station (BS) and at the mobile station (MS). The analysis of the frame‐error rate (FER) and the bit‐error rate (BER) demonstrates the excellent performance of the proposed high data rate super‐orthogonal ST trellis code. Copyright © 2006 AEIT.

Recognition of design symbols from midship drawings

Despite the availability of 3D CAD systems, the designers in shipyards still use 2D CAD systems because of the need to produce drawings rapidly and a shortage of labor. The shipyard spends much time and labor analyzing the design information contained in 2D drawings and creating 3D model for the downstream processes. The design information is represented by symbols that are well known among designers in shipyard. Symbols are expressed by meaningless geometric shapes. These shapes are recognized to have meanings by analysis of experienced and knowledgeable designers. We propose a method for automatic recognition of 2D symbols and the extraction of design information from the midship drawings. The shape and rationale of 2D symbols used in ship design have been analyzed, and symbols have been classified according to the analysis. Based on the classified symbols, the developed system recognizes the symbols expressed in 2D drawings. The extracted design information is assorted by design rationales. The meaningless geometric shape is translated into the design information including designer's intents. The extracted design data can be applied to the design process in shipyards, and the 3D ship model can be automatically created.

중앙단면도 상의 심볼 인식법을 통한 설계정보의 추출

Despite the availability of 3D CAD systems, the designers in shipyards still use 2D CAD systems because of the need to produce drawings rapidly and a shortage of labor. The design information of ship structure contained in 2D drawings is represented by symbols that are well known among designers in shipyard. The shapes of symbols are recognized by analysis of experienced and knowledgeable designers. We propose a method for automatic recognition of 2D symbols and extraction of design information from the midship drawings. The shape and rationale of 20 symbols used in ship design have been analyzed, and symbols have been classified according to the analysis. Based on the classified symbols, the developed system recognizes the symbols expressed in 2D drawings. The meaningless geometric shape is translated into the design information including designer's intents. The extracted design data can be applied to the downstream design process in shipyards, and the 3D ship model can be automatically created.