Original Bit Research Articles

Optimization of hydraulic structure and well flushing parameters of a truncated cone drill bit for drilling shaft sinking

ABSTRACT Based on a research method combining numerical simulations and model testing, a numerical model and test platform for gas lift reverse circulation multiphase coupling in well washing were developed. The hydraulic structure and well washing parameters of a φ5 m truncated cone bit used in the Beifeng well at Taohutu Coal Mine were optimized, and the distribution law of the well washing flow field was determined. The findings revealed that: (1) with a bit taper of 40 and a length-diameter ratio of 0.32 for the truncated cone, the hydraulic structure was optimal. Compared with the original bit structure, the axial speed of mud at the slag suction port increased by 15.9%, and the average sliding speed of mud at the inclined rock surface increased by 63.2%. (2) The multiphase fluid in the slag discharge pipe flowed successively in the form of “low-speed stable two-phase flow” and “high-speed disordered three-phase flow,” while the multiphase fluid in the horizontal and inclined bottom holes flowed predominantly in radial and tangential patterns, respectively. (3) The optimal parameter combination for efficient well washing with the truncated cone bit included a bit rotation speed of 8 r/min, a gas injection rate of 5600 m3/h, an air duct sinking ratio of 0.79, and a mud viscosity of 176 mPa·s, with bit rotation speed being the most significant factor affecting effective washing efficiency. These results could provide a valuable reference for improving the efficiency of drilling and well flushing in Jurassic strata of western China.

Information hiding using approximate POSIT representation

AbstractPOSIT is a numerical system consists of sign, regime, exponential, and fraction bits to overcome some limitations of the IEEE‐754 floating point (FP) representation. This work proposes a technique to hide critical information in the least significant bits (LSBs) of the POSIT FP representation by exploiting approximate computing (AC). The proposed technique, called information hiding using POSIT and LSB (IHUPL), explores the opportunities offered by both the POSIT representation and the AC to hide information with a minimum loss in accuracy and other performance metrics. IHUPL offers two options for hiding information: either by embedding one digit of each character into each pixel or by embedding all the digits of the character at the same time into each pixel of the alpha‐red, green, blue, or black/white image. Experimental results are evaluated for benchmark images and showed that IHUPL enhanced the accuracy of embedding data into LSB of POSIT FP by an average of 5%, the image quality improvement rates of IHUPL are 19% and 16% for options 1 and 2, respectively. Besides the encoding method using IHUPL, the paper outlines an extraction decoding technique that saves the original replacement bits in a key‐image to recover the hidden security message.

Polar coded SCMA-OCDM based on chaotic scrambled SLM.

In this work, the polar coded sparse code multiple access (SCMA) scheme based on chaotic scrambled selective mapping (CS_SLM) is proposed for future passive optical networks (PONs). The original bits are coded by polar and mapped into constellation symbols by sparse code. Then orthogonal chirp division multiplexing (OCDM) modulation is adopted which has better anti-interference ability than orthogonal frequency division multiplexing (OFDM). At the receiver, the joint iterative detection and decoding for polar and SCMA is used to further improve the BER performance. The CS_SLM is helpful to improve the reliability and security, while keeping high spectral efficiency of SCMA-OCDM modulation. A 49.42 Gb/s coded SCMA-OCDM PON over 2 km seven-core fiber is demonstrated in the experiment. The results show that the SCMA-OCDM scheme gets a receiver sensitivity of 0.8 dB at a bit error rate (BER) of 3.8 × 10-3, compared with SCMA-OFDM. Because of peak to average power ratio (PAPR), the polar coded SCMA-OCDM based on CS_SLM is compared with clipping and filtering (CAF) method, about 2.08 dB receiver sensitivity gain is obtained when BER is lower than 10-5. The polar coded SCMA-OCDM based on CS_SLM also takes security into the consideration, due to the downlink broadcasting of PON. It can be a promising candidate for the next generation PONs.

Design of intelligent drill bit embedded structure based on multi-objective topology optimization method

To address the issues of mechanical performance changes, stress concentration, and displacement in the original drill bit structure caused by the design of embedded structures in intelligent drill bits, the optimal topology of the drill bit was calculated using multi-objective topology optimization methods. Optimal values under various load conditions were obtained using single-objective topology optimization methods combined with penalty functions. Based on these optimal values, calculations for the intelligent drill bit embedded structure were performed using a trade-off planning method. Following this, the initially optimized results were redesigned using NURBS modeling methods to create an embedded structure that meets structural performance requirements. The embedded structure meeting these requirements was then tested through orthogonal simulation to verify its mechanical performance under various complex load conditions. The results show that the embedded structure drill bits designed based on multi-objective optimization generally surpass traditional drill bit structures and those optimized using multi-objective methods in terms of maximum Mises stress and maximum deformation, particularly in external and internal petal configurations, demonstrating good performance in enhancing structural strength.

Rate 5/6 TCM Code Having 64 States with 64 QAM for Fading Channel

Trellis Coded Modulation (TCM) is powerful technique employed in digital communication systems to improve the reliability and efficiency of data transmission. TCM combines error control coding and modulation schemes to achieve superior performance in challenging channel conditions. In TCM, information bits are encoded using a trellis encoder, which generates a sequence of encoded symbols. These symbols are then mapped onto a modulation scheme, such as Quadrature Amplitude Modulation (QAM) or Phase Shift Keying (PSK), to create the modulated signal. At the receiver, the received signal is demodulated and decoded using a trellis decoder, which employs maximum likelihood decoding to recover the original information bits. The trellis structure allows for efficient error correction and makes TCM particularly suitable for channels with fading, noise, and other impairments. TCM has been widely used in various communication standards and applications to enhance data transmission reliability and spectral efficiency. TCM is a coding technique that merges coding and modulation to attain substantial coding gain without compromising bandwidth efficiency. The emergence of TCM occurred in the late 1970s, and ever since, it has found extensive utilization in various contemporary information transmission systems. In this paper, a new methodology is introduced for the design of a 64-state rate 5/6 TCM code optimized for fading channels. The outcomes obtained from the study are remarkably encouraging, demonstrating coding gain of around 10 dB in comparison to uncoded 32 PSK. This substantial gain plays a pivotal role in boosting data rates, especially in situations where bandwidth-limited channels are involved.

LDPC-coded cylindrical vector beam multiplexing for improved communication performance

Cylindrical vector beams (CVBs) have attracted significant research interest in mode-division multiplexing communication thanks to their capacity to carry orthogonal vector modes. Because CVB modes are the eigen-solutions of few-mode fiber (FMF), they are well-suited for long-distance transmission. Nevertheless, the application of CVB multiplexing communication is impeded by mode coupling in FMF, which leads to mode crosstalk and signal fading. Herein we propose an LDPC coded strategy to provide a channel equalization solution, which enhances the performance of CVB multiplexing communication. Digital signals are encoded using a sparse parity-check matrix that establishes a specific parity-check relationship between the original data bits and the check bits. This enables the correction of error bits for channel equalization. To demonstrate the concept, we built a 4-channel CVB multiplexing communication system that transmitted 24 × 4 Gbit/s QPSK-OFDM signals over 5 km FMF. After equalization, the bit error rate decreased by ∼ 2.5 orders of magnitude, and the communication sensitivity improved by ∼ 8 dB. This proof of concept demonstrates the potential of the proposed LDPC coded strategy to enhance the performance of CVB multiplexing communication systems.

Massive capacity of novel three‐dimensional OCDMA‐FSO system for next generation of high‐data wireless networks

AbstractThe present study examines an interesting wireless system known as spectral/temporal/spatial‐optical code division multiple access‐free space optics (OCDMA‐FSO) by integrating the new three‐dimensional successive weight (3D‐SW) code for the incoherent system. The system is proposed to be adopted in future generations of wireless networks in view of its attractive features such as simple architecture, high data rate, strong immunity against electromagnetic interference, and optimal power consumption. Furthermore, the recommended code has a zero cross‐correlation (ZCC) feature that removes multiple access interference (MAI) and lowers the effect of phase‐induced intensity (PIIN) noise, which primarily affects OCDMA performance. Meanwhile, an original bit error rate (BER) formulation based on the signal‐to‐noise ratio (SNR) calculation has been developed. The computational results clarified that a recommended approach improves optical system efficacy by boosting numerous analytical criteria. Firstly, the numerical outcomes exhibit that the proposed system improves cardinality by 3.67, 3.08, 2.19, and 5 times than the systems using three‐dimensional perfect difference (3D‐PD), both three‐dimensional perfect difference/multi diagonal (3D‐PD/MD) and three‐dimensional‐dynamic cyclic shift/multi diagonal (3D‐DCS/MD), two‐dimensional‐SW, and one‐dimensional‐SW codes, respectively. Further, It saves roughly −7.3 dBm and − 4.2 dBm when moving from (1D) and (2D) to (3D). Second, the implementation of the proposed model under Optisystem software reveals that the system is compatible with optical communication norms and can be used in upcoming generations of wireless networks, where it achieves BER of with better transmission quality reaching 12.09 at a high bit rate until 30 Gbps across a wireless distance up to 6 km.

An efficient ultra-wideband digital transceiver for wireless applications on the field-programmable gate array platform

<p>The ultra-wideband (UWB) technology is a promising short-range communication technology for most wireless applications. The UWB works at higher frequencies and is affected by interferences with the same frequency standards. This manuscript has designed an efficient and low-cost implementation of IEEE 802.15.4a-based UWB-digital transceiver (DTR). The design module contains UWB transmitter (TX), channel, and UWB-receiver (RX) units. Convolutional encoding and modulation units like burst position modulation and binary phase-shift keying modulation are used to construct the UWB-TX. The synchronization and Viterbi decoder units are used to recover the original data bits and are affected by noise in UWB-RX. The UWB-DTR is synthesized using Xilinx ISE<sup>®</sup> environment with Verilog hardware description language (HDL) and implemented on Artix-7 field-programmable gate array (FPGA). The UWB-DTR utilizes less than 2% (slices and look-up table/LUTs), operates at 268 MHz, and consumes 91 mW of total power on FPGA. The transceiver achieves a 6.86 Mbps data rate, which meets the IEEE 802.15.4a standard. The UWB-DTR module obtains the bit error rate (BER) of 2×10<sup>-4</sup> by transmitting 105 data bits. The UWB-DTR module is compared with similar physical layer (PHY) transceivers with improvements in chip area (slices), power, data rate, and BER. </p>

ELDPC: An Efficient LDPC Coding Scheme for Phase-Change Memory

Low read latency, long lifetime, and high storage density have all been demonstrated in phase-change memory (PCM), making it an attractive contender for main memory. However, due to resistance drift per cell caused by long-term storage, data reliability becomes a major challenge. Low-density parity-check (LDPC) codes with improved error correction capability can be used in PCM to reduce bit error rates and thus improve data reliability. More interestingly, when the raw bit error rates (RBER) of various pages in PCM is compared at the same storage time, a considerable gap appears, resulting in high sensing and decoding latency. We propose eLDPC, an efficient LDPC coding scheme for reducing sensing and decoding latency, in this paper. We start with a preliminary experiment, which reveals that there is a significant variation in resistance drifts between adjacent distributions, resulting in a large RBER gap for different pages. Then, using a submatrix of the parity-check matrix to shorten the codeword length, eLDPC is inspired to encode pages with lower RBER. The original bit sequence is separated into even bit sequence (EBS) and odd bit sequence (OBS) for pages with higher RBER. eLDPC is used to encode EBS and OBS independently. By utilizing optimized soft information, EBS and OBS are eLDPC decoded. eLDPC can significantly improve error correction capability of LDPC hard decoding, effectively eliminating soft decoding processes and lowering decoding latency. The results of simulations show that eLDPC can greatly decrease decoding iterations and time.

E-BiT: Extended Bio-Inspired Texture Descriptor for 2D Texture Analysis and Characterization

This paper presents an extended bio-inspired texture (E-BiT) descriptor for image texture characterization. The E-BiT descriptor combines global ecological concepts of species diversity, evenness, richness, and taxonomic indexes to effectively capture texture patterns at local and global levels while maintaining invariance to scale, translation, and permutation. First, we pre-processed the images by normalizing and applying geometric transformations to assess the invariance properties of the proposed descriptor. Next, we assessed the performance of the proposed E-BiT descriptor on four datasets, including histopathological images and natural texture images. Finally, we compared it with the original BiT descriptor and other texture descriptors, such as Haralick, GLCM, and LBP. The E-BiT descriptor achieved state-of-the-art texture classification performance, with accuracy improvements ranging from 0.12% to 20% over other descriptors. In addition, the E-BiT descriptor demonstrated its generic nature by performing well in both natural and histopathologic images. Future work could examine the E-BiT descriptor’s behavior at different spatial scales and resolutions to optimize texture property extraction and improve performance.

Reversible Data Hiding in Encrypted Images Based on an Adaptive Recognition Strategy for Blocks

As the rapid development of third-party storage and homomorphic encryption have profoundly stimulated the desire for secure communication, reversible data hiding in encrypted images has received widespread attention, since it allows lossless data conveying and perfect image recovery. In order to obtain secure reversible data hiding with high embedding capacity, a novel block embedding method is proposed, based on an adaptive recognition strategy for combined blocks in the binary image, with which the adjacent identical blocks can be integrated into a combination to reserve more spare bits for data accommodation. Furthermore, a fully reversible data hiding method for grayscale images in the encryption domain is designed. The secret data is hidden into lower bit-planes of the image while the original bits of those embedded lower pixels are recorded into the vacated space of higher bit-planes. The original image can be reconstructed flawlessly as well as the secret data being extracted without errors. To reinforce security, the original image and the secret data are encrypted and scrambled based on sequences generated with the high-dimension chaotic system. Due to its high sensitivity of initial values, the performance such as security and robustness is guaranteed. By comparing the PSNR value of the marked decrypted image and evaluating the quality of the extracted secret image, experimental results demonstrate that the proposed method can obtain higher embedding capacity, achieving 0.2700–0.3924 bpp increment over the state-of-the-art methods, and recover the marked decrypted image with high visual symmetry/quality, and efficiently resist against potential attacks, such as the histogram analysis, differential, brute-force, JPEG attacks, and so on.

Trialling Locally Made, Low-Cost Bits to Improve Bit-Related Welfare Problems in Cart Horses: Findings from a Study in Senegal

Bits used for cart horses in Senegal are typically made of recovered construction iron and often have defects related to design, shape, fit and metal quality. Consequently, there is widespread presence of bit-related oral injury amongst these equids. It was hypothesised that improving bit design would ameliorate bit-related welfare issues for working cart horses. This study aimed to develop locally made alternative bit prototypes and test their efficacy as less harmful to working horses, and their acceptability to their drivers. Eight animal-based welfare indicators (four physical and four behavioural) were designed to measure positive or negative effects of the new bits. Following a testing phase to appraise and mitigate potential animal welfare risk associated with the alternative bit designs, a total of 540 driver/horse combinations were opportunistically selected across five municipalities in Senegal. Welfare indicators were observed when new bits were introduced and again after 21 weeks of daily use. The results indicated statistically significant improvements in all welfare indicators measured (i.e., lesions on lip commissures, tongue, buccal mucosa and bars; and open mouth, tongue loll, head toss/shake, and head tilt/turn behaviours). None of the drivers reported any difficulty with horse control, nor chose to revert back to their original bits. Whilst acknowledging the limitation of inability to control all potential confounding variables, these preliminary findings suggest the bit itself as an important contributor to oral injury, and the possibility to improve this through alternative bit design that is low-cost, locally produced and acceptable to drivers.

Base41: A proposal for printable encoding of bit strings

AbstractThis article presents the proposal of a novel encoding method for representing binary data in printable format. The encoding procedure reversibly transforms binary strings into printable letter sequences using a mapping from bit strings to an alphabet of 41 symbols taken from a subset of the English uppercase and lowercase letters. The decoding process reversibly recovers an original bit string from the encoded printable string. The encoding and decoding algorithms along with the properties of this coding are examined and discussed. In particular, the use of only URL‐safe and clearly visually distinguishable characters is emphasized.

Design and Implementation of Adaptive Universal Filtered Multi Carrier for 5G and Beyond

The current generation (5G) mobile communication system promises to accommodate a wide range of new applications and use scenarios, resulting in more flexible and unified connection. To satisfy the required criteria, the current waveform was replaced with new UF-OFDM, which combines the advantages of OFDM with enhanced spectral characteristics and greater resilience against time-frequency misalignments. However, its biggest disadvantage is the transmitter's computational complexity, which may be up to two hundred times that of OFDM if there is no reduction in complexity. The majority of current research on unique waveforms has focused on filter modification or performance enhancement strategies. UFMC with the use of adaptive filter (UFMC -FSK) is offered as a revolutionary technique in this study. The filter designed and used to transport information through the index modulation technique. As a result, each UF-OFDM sub band's used filter is chosen, so the data rate is enhanced according to a filter configured depending on original input data bits. The combined Maximum-likelihood (ML) decision metric for each sub band that is calculated at the receiver. Each sub band has a filter as well as data symbols that provide the minimal metric for making decisions are discovered. Furthermore, the bit error rate and power spectrum density are enhanced over the UF-OFDM technique, however there is some trade-off. Overall, the proposed system outperform typical UF-OFDM. Matlab simulations are used to assess the performance of the Adaptive UFMC system.

Robust Watermarking Scheme for Vector Geographic Data Based on the Ratio Invariance of DWT–CSVD Coefficients

Traditional frequency-domain watermarking algorithms for vector geographic data suffer from disadvantages such as the random watermark embedding position, unpredictable embedding strength, and difficulty in resisting multiple attacks at the same time. To address these problems, we propose a novel watermarking algorithm based on the geometric invariance of the ratios of discrete wavelet transform (DWT) and complex singular value decomposition (CSVD) coefficients, which embeds the watermark information in a new embedding domain. The proposed scheme first extracts feature points from the original vector geographic data using the Douglas–Peucker algorithm, and then constructs a complex sequence based on the feature points set. The two-level DWT is then performed on the complex sequence to obtain the low frequency coefficients (L2) and high frequency coefficients (H2). On this premise, the CSVD algorithm is utilized to calculate the singular values of L2 and H2, and the ratio of the singular values of L2 and H2 is acquired as the watermark embedding domain. During the watermark embedding process, a new watermark sequence is created by the fusion of the original watermark index value and bits value to improve the recognition of the watermark information, and the decimal part at different positions of the ratio is altered by the new watermark sequence to control the watermark embedding strength. The experimental results show that the proposed watermarking algorithm is not only robust to common attacks such as geometric, cropping, simplification, and coordinate point editing, but also can extract watermark images with a high probability under random multiple attacks.

Mine Intelligent Receiver: MIMO-OFDM Intelligent Receiver for Mine Information Recovery

With the advancement of an intellectual and numerical society, the coal mining industry has also begun to change to intelligence. As an important aspect of intelligent coal mine construction, coal mine communication has put forward more stringent standards for communication quality. For the complex communication environment in mines, the transmission of communication signals is always damaged by various noises and interferences, resulting in serious distortion of the communication signals received at the receiving end. Therefore, the use of traditional receivers for information recovery has the problem of high bit error rate (BER), which cannot meet the standard of intelligent coal mine construction. Based on this, the aim of this research is to combine convolutional neural networks (CNN) and multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) communication systems to design an intelligent receiver model for complex mine communication systems. At the receiver side, CNNs are used to take the place of all the information processing processes. First, features are extracted from the received IQ signal by the convolutional neural network, and then the original information bit is recovered using a multi-label classifier to finally realize end-to-end information restoration. The experimental results show that the intelligent receiver model designed in this research has more accurate information recovery capability in the complex mine channel environment compared with the traditional receiver. In addition, they also verify that the intelligent receiver can still recover information effectively when the traditional receiver cannot recover information properly in the case of partial loss of received data.

Optimal Neuro-Fuzzy Equalizers for Detecting Nonlinear Distortion Channels of the Perpendicular Magnetic Recording System

Nonlinear distortions caused by partial erasure and nonlinear transition shifts interacting with inter-symbol interference, are a major hindrance to data storage systems, since they degrade detector performance. This work aims to design and optimize the neuro-fuzzy equalizer (NFE) using the multi-objective genetic algorithm (MOGA) to detect nonlinear high-density magnetic recording (MR) channels. Through the GA-assisted back-propagation algorithm and least mean square optimization, the complexity in terms of decision rules is reduced by 25% and significantly provides 65% lower signal processing computation. When applied to the perpendicular (MR) system, the proposed NFE outperforms existing equalizers such as the neural network-based equalizer, fuzzy logic equalizer, and conventional NFE for the Volterra and jitter media noise channels using 1–3 dB and 1.5–3.5 dB signal-to-noise ratio gains at the bit-error-rate of 10-4, respectively. Furthermore, compared to the other models, the NFE provides a more effective output mean square error performance for retrieving the original bit data.

FBMC/OQAM Security Strategy Based on Diversity DNA Encryption

In this paper, a diversity deoxyribonucleic acid (DNA) chaotic encryption strategy is proposed to enhance the physical layer security of the filter bank multi-carrier/offset quadrature amplitude (FBMC/OQAM) system. After the input original binary bit stream is encrypted, it is subjected to FBMC/OQAM modulation. The encryption process of bit data is dynamically controlled by the chaotic sequences generated by the hybrid chaotic system composed of improved-Logistic and delayed tent sine system, which enhances the robustness against malicious attacks by illegal attackers. The diversity DNA encryption strategy expands the key space of the system to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">180</sup> , which can ensure the physical layer security of the system. The proposed FBMC/OQAM security strategy based on chaotic encryption is transmitted on 25 km standard single mode fiber. Experimental results show that the diversity DNA encryption strategy can effectively ensure the security of transmitted data.

Experimental demonstration of 50-m/5-Gbps underwater optical wireless communication with low-complexity chaotic encryption.

In this paper, a low-complexity two-level chaotic encryption scheme is introduced and experimentally demonstrated to improve the physical layer security of a 450-nm laser underwater optical wireless communication (UOWC) system using discrete Fourier transform spread discrete multi-tone (DFT-S DMT) modulation. In the first encryption stage, the original bit stream is encrypted with a chaotic sequence based on a one-dimensional Logistic map. In the second encryption stage, the real and imaginary components of the DFT-S symbols are further encrypted with a pair of separate chaotic sequences, which are generated from a two-dimensional Logistic iterative chaotic map with infinite collapse (2D-LICM). The experimental results indicate that the encryption operation has no negative effect on the performance of the proposed UOWC system. For chaotic encryption, the DFT-S DMT gives a better performance than the DMT scheme under different water turbidities. 55-m/4.5-Gbps and 50-m/5-Gbps underwater transmissions are successfully demonstrated by the chaotic encrypted DFT-S DMT scheme. To the best of our knowledge, this is the first time to verify the feasibility of chaotic encryption in a high-speed UOWC system.

Chaotic image encryption algorithm based on arithmetic sequence scrambling model and DNA encoding operation

In this paper, in order to solve the problem of un-rigorous scrambling method and single diffusion method in image encryption, a new method based on arithmetic sequence scrambling model, DNA coding sequence and one-dimensional Logistic mapping is proposed. First, the Hash array is obtained by combining the information of the original plaintext image with the Hash algorithm SHA-512. The Hash array generates the initial value and control parameters of the chaotic system, and then generates the chaotic key flow. Second, the arithmetic progression of partitioned matrix after scrambling, change the position of the original image pixels, replacement and operation, and then for DNA combines images and the chaotic sequence of chaotic system to produce DNA, DNA encoding, decoding rules for operation, change the original data bits of pixel values, thus further destruction of the original information. Finally, a chaotic diffusion operation is performed to further change the pixel information of the original image and output the cipher-text image. The experimental results and various security analyses show that the algorithm has good encryption effect and can resist the common plaintext attack, clipping attack and noise attack. The algorithm can be used for image encryption.