Block Codes Research Articles

A Deep Learning-based Approach for Channel Estimation in Multi-access Multi-antenna Systems

This paper studies estimating the channel state information at the end of receiver (CSIR) for multiple transmitters communicating with only one receiver so that the latter can decode the incoming signal more efficiently. The transmitters and the receiver are all equipped with multi-antennas and using orthogonal space-time block codes (OSTBC). An algorithm is developed based on deep learning for estimating multi-user multiple-input multiple-output (MU-MIMO) channels. The algorithm could estimate the CSIR using a single pilot block. The proposed convolutional neural network (CNN) architecture designed for this task begins with an input layer that accepts grayscale images, followed by six convolutional blocks for feature extraction and processing. The network concludes with a fully connected layer to output the estimated channel information. It is trained using a regression loss function to map input images to accurate channel information accurately. The performance of the proposed method is compared with classical methods like least square and subspace-based methods, including Capon and rank revealing QR (RRQR) methods. CNN achieved better performance in comparison with the reference. Computer simulations are included to validate the proposed method.

Performance Enhancement for B5G/6G Networks Based on Space Time Coding Schemes Assisted by Intelligent Reflecting Surfaces with Higher Modulation Orders.

Intelligent Reflecting Surfaces (IRS) and Multiple-Input Single-Output (MISO) technologies are essential in the fifth generation (5G) networks and beyond. IRS optimizes the signal propagation and the coverage and is a viable approach to address the issues caused by fading channels that limits the spectral efficiency, while MIMO enhances data rates, reliability, and spectral efficiency by using multiple antennas at both transmitter and receiver ends. This paper proposes an IRS-assisted MISO system using the Orthogonal Space-Time Block Code (OSTBC) scheme to enhance the channel reliability and reduce the Bit Error Rate (BER) in wireless communication systems. The proposed system exploits the benefits from the transmit diversity gain of the OSTBC scheme as well as from the bit energy to noise power spectral density (Eb/No) improvement of the IRS technology. The presented work explores these combined technologies across different modulation schemes. The obtained results outperform the similar previously published works by considering higher-order modulation schemes as well as the deployment of rate ¾ OSTBC-assisted IRS. Moreover, the obtained results demonstrate that the integration of OSTBC with IRS can yield significant performance improvements in terms of Eb/No by 7 dB and 13 dB when using 16 reflecting elements and 64 reflecting elements, respectively.

Oppositely charged polymer-surfactant nanoparticles stabilized by triblock copolymers for enhanced oil loading

When oppositely charged polymers and surfactants combine, they can form a concentrated phase rich in micelles interconnected by polymer chains. Dispersing this concentrated phase as nanoparticles in an aqueous media can be a way to load and deliver hydrophobic ingredients. This study employed triblock copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), EOxPOyEOx, also known as poloxamers or pluronics, to disperse the concentrated phase, forming nanoparticles of aggregated micelles connected by the polyion chains. We showed that nanoparticles formed by hexadecyltrimethylammonium bromide (CTAB), poly(acrylic acid) (PAA), and different EOxPOyEOx copolymers can enhance the loading of oily ingredients compared to pure surfactant micelles. Dispersions with 1.6 wt% of nanoparticles exhibited water-like viscosity and loaded up to 0.48 wt% of oil. Characterization techniques, including dynamic light scattering (DLS), electrophoretic mobility, small-angle X-ray scattering (SAXS), and cryogenic transmission electronic microscopy (cryo-TEM), revealed positively charged spherical 50–180 nm nanoparticles with a core formed by concentrated micelles, that were stable for at least 4 months. Variations in the EO and PO block lengths did not impact morphology, showing that different EOxPOyEOx copolymers were suitable for dispersing the nanoparticles. Increasing EO block length size decreased the diameter of nanoparticles and enhanced stability, providing a means to control their properties. In conclusion, nanoparticles formed by oppositely charged polymer-surfactant mixtures and stabilized by triblock copolymers showed potential for applications, such as sprays, due to their effective oil loading, high stability, and facile preparation.

Flag-transitive 2-designs with prime-square or prime-cube block length

Flag-transitive 2-designs with prime-square or prime-cube block length

Tailoring copolymer architectures and macromolecular interactions for enhanced nanotherapeutic delivery: A design-by-architecture approach

Amphiphilic copolymers with precise macromolecular topologies are crucial in nanomedicine for enhancing drug delivery by improving solubilization, stabilization, and therapeutic efficacy on target tissues. This study employs a design-by-architecture approach to identify factors influencing interactions between synthesized macromolecules and biological systems for optimal drug nanodelivery. Copolymers combining poly(ε-caprolactone) blocks and poly(polyethylene glycol methacrylate) or poly(glycerol methacrylate), were synthesized to investigate how architectural adjustments impact self-assembly, nanoparticle size, drug loading, and biomolecule interactions. Linear and brush block copolymers with varied block lengths were studied for their self-assembly behavior in aqueous environments. Both copolymer types formed smaller nanoparticles with extended hydrophilic blocks, with brush block copolymers showing superior performance due to their peculiar macromolecular architecture. Incorporating ‘clickable’ glycidyl units within the hydrophilic block minimally affected particle size. Controlled functionalization with thiol groups resulted in stable nanoparticles with enhanced size reduction and mucoadhesive properties, potentially improving targeted drug delivery and therapeutic effects.

Constacyclic codes over F q S T and their applications

Let q = p r , where p is an odd prime and r is a positive integer. Consider a ring F q S T , where S = F q + u F q + v F q + uv F q with u 2 = 1 , v 2 = 1 , uv = vu and T = F q + u F q + v F q + w F q + uv F q + uw F q + vw F q + uvw F q with u 2 = 1 , v 2 = 1 , w 2 = 1 , uv = vu , uw = wu , vw = wv . In this paper, we examine the algebraic structure of constacyclic codes over the ring F q S T of block length ( α , β , γ ) . Further, a construction of quantum error-correcting codes (QECCs) from constacyclic codes over F q S T is also given. Moreover, we derive a number of new QECCs.

Block encodings of discrete subgroups on a quantum computer

We introduce a block encoding method for mapping discrete subgroups to qubits on a quantum computer. This method is applicable to general discrete groups, including crystal-like subgroups such as BI of SU(2) and V of SU(3). We detail the construction of primitive gates—the inversion gate, the group multiplication gate, the trace gate, and the group Fourier gate—utilizing this encoding method for BT and for the first time BI group. We also provide resource estimations to extract the gluon viscosity. The inversion gates for BT and BI are benchmarked on the quantum computer with estimated fidelities of 40−4+5% and 4−3+5%, respectively. Published by the American Physical Society 2024

Factorizers for distributed sparse block codes

Distributed sparse block codes (SBCs) exhibit compact representations for encoding and manipulating symbolic data structures using fixed-width vectors. One major challenge however is to disentangle, or factorize, the distributed representation of data structures into their constituent elements without having to search through all possible combinations. This factorization becomes more challenging when SBCs vectors are noisy due to perceptual uncertainty and approximations made by modern neural networks to generate the query SBCs vectors. To address these challenges, we first propose a fast and highly accurate method for factorizing a more flexible and hence generalized form of SBCs, dubbed GSBCs. Our iterative factorizer introduces a threshold-based nonlinear activation, conditional random sampling, and an ℓ ∞ -based similarity metric. Its random sampling mechanism, in combination with the search in superposition, allows us to analytically determine the expected number of decoding iterations, which matches the empirical observations up to the GSBC’s bundling capacity. Secondly, the proposed factorizer maintains a high accuracy when queried by noisy product vectors generated using deep convolutional neural networks (CNNs). This facilitates its application in replacing the large fully connected layer (FCL) in CNNs, whereby C trainable class vectors, or attribute combinations, can be implicitly represented by our factorizer having F-factor codebooks, each with C F fixed codevectors. We provide a methodology to flexibly integrate our factorizer in the classification layer of CNNs with a novel loss function. With this integration, the convolutional layers can generate a noisy product vector that our factorizer can still decode, whereby the decoded factors can have different interpretations based on downstream tasks. We demonstrate the feasibility of our method on four deep CNN architectures over CIFAR-100, ImageNet-1K, and RAVEN datasets. In all use cases, the number of parameters and operations are notably reduced compared to the FCL.

Improved Quantum Rebound Attacks on Double Block Length Hashing with Round-Reduced AES-256 and ARIA-256

At EUROCRYPT 2020, Hosoyamada and Sasaki proposed the first dedicated quantum collision attacks on hash functions. Their proposal presented a quantum adaptation of the rebound attack and revealed that differential trails, which have too low probability for use in classical settings, might be exploitable in quantum settings. After their work, subsequent research has actively delved into analyzing the security of hash functions in the quantum setting.In this paper, we revisit the quantum rebound attacks on the double block hash function Hirose instantiated with 10-round AES-256 (HCF-AES-256) and 7-round ARIA-256 (HCF-ARIA-256) proposed by Chauhan et al. and Baek et al., respectively. Initially, we identify the flaws in their work and reevaluate the complexity of the attacks. We reveal that the flaws stem from not considering the issue that the S-box differential equation has one solution on average. Earlier research addressed this problem by adding auxiliary bits to the search space. If this method is used to correct the flaws, the resulting time complexities are 217.36 and 220.94 times higher than their proposals. Consequently, in some settings, their attacks become less efficient than generic attacks.Subsequently, we propose improved quantum rebound attacks using nested quantum amplitude amplification and quantum state preparation. Our improved attack efficiently pre-filters the search space, leading to a reduction in overall time complexity. We first classically reduce the search space and employ quantum state preparation to generate a superposition state over the pre-filtered search space. We then use nested quantum amplitude amplification to further reduce the search space quantumly. As a result, we achieve a reduction in the time complexity of the quantum rebound attacks on HCF-AES-256 and HCF-ARIA-256 by factors of 211.2 and 219.5, respectively, making the attacks more efficient than generic attacks again.

DNA Hierarchical Superstructures from Micellar Units: Stiff Hydrogels and Anisotropic Nanofibers.

Supramolecular materials have been assembled using a wide range of interactions, including the hydrophobic effect, DNA base-pairing, and hydrogen bonding. Specifically, DNA amphiphiles with a hydrophobic building block self-assemble into diverse morphologies depending on the length and composition of both blocks. Herein, we take advantage of the orthogonality of different supramolecular interactions - the hydrophobic effect, Watson-Crick-Franklin base pairing and RNA kissing loops - to create hierarchical self-assemblies with controlled morphologies on both the nanometer and the micrometer scales. Assembly through base-pairing leads to the formation of hybrid, multi-phasic hydrogels with high stiffness and self-healing properties. Assembly via hydrophobic core interactions gives anisotropic, discrete assemblies, where DNA fibers with one sequence are terminated with DNA spheres bearing different sequences. This work opens new avenues for the bottom-up construction of DNA-based materials, with promising applications in drug delivery, tissue engineering, and the creation of complex DNA structures from a minimum array of components.

PIV investigation of the effects of simulated ice blocks on the turbulent flow dynamics around a partially submerged horizontal circular cylinder

This paper presents a novel particle image velocimetry study of the effects of stationary upstream ice blocks on the turbulent flow dynamics around a single, fixed ice boom pontoon. The pontoon was modelled using a half-submerged horizontal circular cylinder. Different lengths, thicknesses, and undersurfaces of the ice blocks were examined. The Reynolds number was maintained at 25,500. The results show that the cylinder encounters an approach flow with lower momentum but higher turbulence intensity when placed behind a long ice block compared to a shorter one, and the presence of undersurface roughness reduces the momentum but enhances the turbulence intensity of the approach flow. The recirculation length, mean velocities, and turbulence levels around the cylinder reduce with increasing ice block length and subsequent roughening of its undersurface. However, a larger recirculation bubble forms from the ice block, and the mean velocities and turbulence levels increase when the ice block thickness increases.

A path splitting and pruning strategy on list decoder for PAC codes

AbstractRecently, Arıkan proposed a polarization‐adjusted convolutional (PAC) codes, demonstrating their superior error correction performance over polar codes at short block lengths. It was confirmed that PAC codes approached the optimal performance achievable with limited code length. This paper proposes a novel low‐complexity list decoding algorithm for PAC codes, incorporating path splitting and pruning strategies based on a set of highly reliable information bits. Simulation results reveal that the proposed algorithm significantly reduces sorting complexity and average list size, all while incurring negligible performance loss. Unlike previous pruning algorithms designed for polar codes, the proposed strategy eliminates the need to individually assess the reliability of decoding paths in each decoding process. Instead, the algorithm minimizes redundant decoding paths through a high‐reliability information bit set, constructed using Monte Carlo experiments.

Using multiple, dynamically linked representations to develop representational competency and conceptual understanding of the earthquake cycle

Using computational methods to produce and interpret multiple scientific representations is now a common practice in many science disciplines. Research has shown students have difficulty in moving across, connecting, and sensemaking from multiple representations. There is a need to develop task-specific representational competencies for students to reason and conduct scientific investigations using multiple representations. In this study, we focus on three representational competencies: 1) linking between representations, 2) disciplinary sensemaking from multiple representations, and 3) conceptualizing domain-relevant content derived from multiple representations. We developed a block code-based computational modeling environment with three different representations and embedded it within an online activity for students to carry out investigations around the earthquake cycle. The three representations include a procedural representation of block codes, a geometric representation of land deformation build-up, and a graphical representation of deformation build-up over time. We examined the extent of students' representational competencies and which competencies are most correlated with students’ future performance in a computationally supported geoscience investigation. Results indicate that a majority of the 431 students showed at least some form of representational competence. However, a relatively small number of students showed sophisticated levels of linking, sensemaking, and conceptualizing from the representations. Five of seven representational competencies, the most prominent being code sensemaking (η2 = 0.053, p < 0.001), were significantly correlated to student performance on a summative geoscience investigation.

Double ended frequency-scanning heterodyne interferometer for absolute length measurement of opaque blocks

A new contactless method based on frequency-scanning heterodyne interferometry is proposed to measure the absolute length of opaque blocks with fragile reflective surfaces. This method is significant in scientific research, such as determining the absolute length of torsion pendulums in gravitational experiments or test masses in gravitational wave detection programs. In addition to avoiding possible damage caused by contact measurement, this optical setup has the potential for higher measurement accuracy compared to contact measurement apparatuses. Two gauge blocks with nominal lengths of 40 mm and 50 mm are used to test the performance of the proposed interferometer, and the measurement results closely match their nominal lengths. The combined uncertainty is 0.62μm and 0.48μm for the 40 mm and 50 mm gauge blocks respectively.

General Structure and Properties of Cyclic Codes Over \(GF_2\)

This article provides a comprehensive analysis of cyclic codes in GF(2), focusing on their general structure and key properties. Cyclic codes are characterized by their generator polynomials, which define their structure and play a crucial role in encoding and decoding processes. The cyclical shift property, inherent in cyclic codes, facilitates efficient implementation using shift register circuits, making them practical for real-world applications. The discussion highlights the algebraic properties that distinguish cyclic codes from other linear block codes, emphasizing their ability to detect and correct errors.

Fragmentation Kinetics of Block Copolymer Micelles: Effect of Core and Corona Block Lengths

Fragmentation Kinetics of Block Copolymer Micelles: Effect of Core and Corona Block Lengths

Construction of CO2‐based thermoplastic elastomer via combining aliphatic polycarbonate and polyamide: A multiblock copolymer PPC‐mb‐PA6

AbstractA CO2‐based thermoplastic elastomer, poly(propylene carbonate)‐multiblock‐polyamide6 (PPC‐mb‐PA6) copolymer, was constructed through coupling amorphous/soft PPC blocks with crystalline/hard PA6 blocks. The PPC‐mb‐PA6 copolymers with different block length pairs were designed and synthesized, and then fully characterized by structural, thermal, and mechanical analysis. The proton nuclear magnetic resonance (1H‐NMR), diffusion ordered spectroscopy (DOSY), heteronuclear multiple‐bond correlation (HMBC) and gel permeation chromatography (GPC) results confirm that the multiblock sequence structure of PPC‐mb‐PA6. The differential scanning calorimetry (DSC) tests show that all PPC‐mb‐PA6s possess melting points around 179–206°C. The thermal and mechanical analysis indicates improved service temperatures (T5% up to 270°C) and tensile strength ranging from 15.8 to 39.6 MPa with higher PA6 content. The dynamic mechanical analysis demonstrates excellent shape memory effect of PPC‐mb‐PA6 with thermal stimuli responsiveness derived from the micro phase separation between soft PPC and hard PA6 domains. And the characteristic strain fixity parameter (Rf) and deformation recovery rate (Rr) are 98% and 100%, respectively, which are comparable with other excellent shape memory polymers.

Enhancing postoperative analgesia in carotid endarterectomy patients: The potential of ultrasound-guided carotid sheath block combined with superficial cervical plexus block: A randomised trial.

Carotid endarterectomy (CEA) is a common procedure conducted under regional anaesthesia, providing real-time cerebral function monitoring. Many different combinations of regional cervical blocks exist, and most offer adequate analgesia in intraoperative and postoperative recovery. This research compares a superficial cervical plexus block (SCB) alone and combined with an ultrasound (US)-guided carotid sheath block (CSB). The primary objective was to explore the length of the sensory block after combining SCB and CSB. Patients scheduled for nonemergency CEA surgery were randomised into two cohorts. The Subject group (28 participants) received US-guided CSB and SCB. The Control group (31 participants) received only an SCB. Both groups received 0.5% levobupivacaine (2 mg/kg) along with 2% lidocaine (2 mg/kg). The sensory block time and its initiation, analgesia and neutrophil-to-lymphocyte ratio (NLR) were recorded before and after the block. The numeric pain rating scale (NPRS) was used to evaluate analgesia every 2 h for 12 h post block. Analysis of variance, Mann-Whitney U or log-rank test was used to analyse the distinction of selected variables. The demographic characteristics were comparable across the cohorts. The Subject group demonstrated a significantly accelerated onset of sensory block (P = 0.029) and an extended time to first analgesia (P = 0.003). The sensory block was also substantially extended in the Subject group (P = 0.040). Postoperative pain (NPRS ≥1) within the first 12 h was more recurrent in the Control group (P = 0.048). NLR showed minimal disparity between the groups (P = 0.125). Combining SCB and US-guided CSB effectively and safely extends postoperative analgesia for CEA surgery.

Somatic mutation phasing and haplotype extension using linked-reads in multiple myeloma.

Somatic mutation phasing informs our understanding of cancer-related events, like driver mutations. We generated linked-read whole genome sequencing data for 23 samples across disease stages from 14 multiple myeloma (MM) patients and systematically assigned somatic mutations to haplotypes using linked-reads. Here, we report the reconstructed cancer haplotypes and phase blocks from several MM samples and show how phase block length can be extended by integrating samples from the same individual. We also uncover phasing information in genes frequently mutated in MM, including DIS3, HIST1H1E, KRAS, NRAS, and TP53, phasing 79.4% of 20,705 high-confidence somatic mutations. In some cases, this enabled us to interpret clonal evolution models at higher resolution using pairs of phased somatic mutations. For example, our analysis of one patient suggested that two NRAS hotspot mutations occurred on the same haplotype but were independent events in different subclones. Given sufficient tumor purity and data quality, our framework illustrates how haplotype-aware analysis of somatic mutations in cancer can be beneficial for some cancer cases.

Electric buses as an air pollution and meteorological observation network: Methodology and preliminary results

Many local agencies in the United States and other countries are tasked to install air pollution monitoring systems of highly accurate sensors that have high acquisition, operating, and maintenance costs. The need for expanded coverage of air quality measurements across Salt Lake County (SLCO), Utah is being met by mounting air quality and temperature sensors on an expanding fleet of battery electric buses (BEBs). Monitoring air quality from a mobile sensor network provides real-time insights into air pollution patterns at high temporal and spatial resolution. Mobile measurements contribute to assessing residents' exposure to air pollution, facilitating the implementation of cost-effective public health policies and highlighting disparities. The Electric Bus Air Quality Observation Project was launched in SLCO during July 2021 and has collected millions of observations to date. A BEB traveling at typical traffic speeds (~10 m s−1) can provide multiple measurements along city block lengths of up to ~200 m. With careful analysis that factors in the time response of the differing sensors, variability from block-to-block may be attributed to fine-scale factors (e.g., pollution and heat sources, tree shading and urban vegetation, etc.). Preliminary findings showcase the value of increased coverage and resolution. During an extreme heat event in July 2023, both the morning and afternoon temperature readings showed differences of over 6.5 °C (12 °F), primarily as an east-west gradient with similar gradients in ozone. We conclude that temperature and pollutant concentration readings, at fine spatial and temporal resolutions, will facilitate future health studies and equitable policy and mitigation strategies. Our study demonstrates that our partnerships established with governmental, non-profit, and transit agencies facilitate the successful transfer of research and development to operational real-time mobile air quality monitoring.