Cooperative Passive Coherent Location: A Promising 5G Service to Support Road Safety

5G promises many new vertical service areas beyond simple communication and data transfer. We propose CPCL (cooperative passive coherent location), a distributed MIMO radar service, which can be offered by mobile radio network operators as a service for public user groups. CPCL comes as an inherent part of the radio network and takes advantage of the most important key features proposed for 5G. It extends the well-known idea of passive radar (also known as passive coherent location, PCL) by introducing cooperative principles. These range from cooperative, synchronous radio signaling, and MAC up to radar data fusion on sensor and scenario levels. By using software-defined radio and network paradigms, as well as real-time mobile edge computing facilities intended for 5G, CPCL promises to become a ubiquitous radar service which may be adaptive, reconfigurable, and perhaps cognitive. As CPCL makes double use of radio resources (both in terms of frequency bands and hardware), it can be considered a green technology. Although we introduce the CPCL idea from the viewpoint of vehicle-to-vehicle/infrastructure (V2X) communication, it can definitely also be applied to many other applications in industry, transport, logistics, and for safety and security applications

Polymers and Their Application in 3D Printing

Dear Colleagues, Fused filament fabrication, also known as 3D printing, is extensively used to produce prototypes for applications in, e.g., the aerospace, medical, and automotive industries. In this process, a thermoplastic polymer is fed into a liquefier that extrudes a filament while moving in successive X–Y planes along the Z direction to fabricate a 3D part in a layer-by-layer process. Due to the progressive advances of this process in industry, the application of polymeric (or even composite) materials have received much attention. Researchers and industries now engage in 3D printing by implementing numerous polymeric materials in their domain. In this Special Issue, we will present a collection of recent and novel works regarding the application of polymers in 3D printing

Piezoelectric scaffolds for osteochondral defect repair

Osteoarthritis is one of the most prevalent causes of disability affecting nearly 27 million Americans. Osteoarthritis is caused when extensive damage occurs to the articular cartilage later spreading to the underlying subchondral bone, resulting in osteochondral defects. The current clinical therapies aim at regenerating the hyaline cartilage, but instead fibrocartilage forms at the osteochondral defect site, which is inferior in structure and function and fails to integrate with the surrounding tissue. A biomimetic scaffold, which can provide cues similar to the native extracellular matrix, may facilitate osteochondral defect repair. Articular cartilage and bone extracellular matrix have been shown to produce electrical potentials when subjected to mechanical loading. The electrical behavior of cartilage and bone may provide signals for tissue repair and remodeling during injury and homeostasis. Therefore, a piezoelectric scaffold, which is able to generate electrical charge in response to deformation, is investigated in this study for its potential to support hyaline cartilage and bone tissue formation in combination with human mesenchymal stem cells (MSCs). The scaffold is composed of the synthetic polymer, poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE), a biocompatible, piezoelectric polymer. It is hypothesized that piezoelectric scaffolds will promote chondrogenic (cartilage) and osteogenic (bone) differentiation of MSCs. PVDF-TrFE is electrospun to form a fibrous, three-dimensional scaffold (as-spun). PVDF-TrFE scaffolds are further annealed to enhance piezoelectric properties (annealed). The chondrogenic and osteogenic differentiation of MSCs is evaluated on both as-spun and annealed PVDF-TrFE scaffolds in a perfused compression bioreactor system to simulate physiological loading. Electrospun polycaprolactone (PCL) is used as a non-piezoelectric control. Under physiological loading conditions, annealed PVDF-TrFE scaffolds have a higher voltage output compared to as-spun PVDF-TrFE scaffold. In bioreactor cultures, MSC chondrogenic differentiation is promoted on as-spun PVDF-TrFE and osteogenic differentiation is enhanced on annealed PVDF-TrFE scaffolds when compared to PCL control. These results suggest that MSCs differentiation behavior can be impacted by the differences in voltage output from the as-spun and annealed PVDF-TrFE, indicating a role for electromechanical stimulus on MSC differentiation. Therefore, piezoelectric scaffolds have the potential to support cartilage and bone growth for osteochondral defect repair

Stress-induced stabilization of pyrolyzed polyacrylonitrile and carbon nanotubes electrospun fibers

The unique properties of graphitic carbons have gained widespread attention towards their development and application. Carbon materials can be synthesized by thermal decomposition and, more specifically, carbon pyrolysis from polymer precursors. The paper shows the pyrolysis process of polyacrylonitrile (PAN) in the presence of multi-walled carbon nanotubes (MWCNTs) according to different manufacturing process conditions. The electrospinning process of the PAN-MWCNTs solution on multi-plates collectors was firstly analyzed. The morphology and the particles arrangement of the electrospun fibers was studied under scanning and transmission electron microscopes. Moreover, the composite fibrous mats were characterized by RAMAN spectroscopy to identify the effects of a mechanical tension application during the thermal stabilization phase performed before the pyrolysis treatment to obtain carbon fibers from the precursor polymer. The results show that the graphitization of the pyrolyzed fibers is enhanced by the combination of MWCNTs and a mechanical stress applied during the thermal treatment

3D Bioprinting In Bone And Cartilage Regeneration Review

 Bone and articular cartilage degeneration and damage are the most common causes of musculoskeletal disability. 3D bioprinting can help regenerate these structures. Autologous/allogeneic bone and cartilage transplantation, vascularized bone transplantation, autologous chondrocyte implantation, mosaicplasty, and joint replacement are all common clinical and surgical procedures. In vitro layer-by-layer printing of biological materials, living cells, and other biologically active substances using 3D bio printing technology is anticipated to replace the aforementioned repair methods. With the ability to prepare various organs and tissue structures, 3D bio printing has largely solved the issue of insufficient organ donors. Researchers use biomedical materials and cells as discrete materials. Bioprinting cell selection and its use in bone and cartilage repair are the primary topics of discussion in this paper

JOINT DETECTION-STATE ESTIMATION AND SECURE SIGNAL PROCESSING

In this dissertation, joint detection-state estimation and secure signal processing are studied. Detection and state estimation are two important research topics in surveillance systems. The detection problems investigated in this dissertation include object detection and fault detection. The goal of object detection is to determine the presence or absence of an object under measurement uncertainty. The aim of fault detection is to determine whether or not the measurements are provided by faulty sensors. State estimation is to estimate the states of moving objects from measurements with random measurement noise or disturbance, which typically consist of their positions and velocities over time. Detection and state estimation are typically implemented separately and state estimation is usually performed after the decision is made. In this two-stage approach, missed detection and false alarms in detection stage decrease accuracy of state estimation. In this dissertation, several joint detection and state estimation algorithms are proposed. Secure signal processing is indispensable in dynamic systems especially when an adversary exists. In this dissertation, the developed joint fault detection and state estimation approach is used to detect attacks launched by an adversary on the system and improve state estimation accuracy. The security problem in satellite communication systems is studied and a minimax anti-jammer is designed in a frequency hopping spread spectrum (FHSS)/quadrature phase-shift keying (QPSK) satellite communication system

Electrospinning húmedo y sus aplicaciones: una revisión

In wet electrospinning, a natural or synthetic polymer solution is deposited on a non-solvent liquid coagulant used as collector. This technique can create 3D nanofiber scaffolds with better properties (e.g., porosity and high surface area) than those of traditional 2D scaffolds produced by standard electrospinning. Thanks to these characteristics, wet electrospinning can be employed in a wide range of tissue engineering and industrial applications. This review aims to broaden the panorama of this technique, its possible fields of action, and its range of common materials. Moreover, we also discuss its future trends. In this study, we review papers on this method published between 2017 and 2021 to establish the state of the art of wet electrospinning and its most important applications in cardiac, cartilage, hepatic, wound dressing, skin, neural, bone, and skeletal muscle tissue engineering. Additionally, we examine its industrial applications in water purification, air filters, energy, biomedical sensors, and textiles. The main results of this review indicate that 3D scaffolds for tissue engineering applications are biocompatible; mimic the extracellular matrix (ECM); allow stem cell viability and differentiation; and have high porosity, which provides greater cell infiltration compared to 2D scaffolds. Finally, we found that, in industrial applications of wet electrospinning: (1) additives improve the performance of pure polymers; (2) the concentration of the solution influences porosity and fiber packing; (3) flow rate, voltage, and distance modify fiber morphology; (4) the surface tension of the non-solvent coagulant on which the fibers are deposited has an effect on their porosity, compaction, and mechanical properties; and (5) deposition time defines scaffold thickness.  En el electrospinning húmedo, se deposita una solución de polímero natural o sintético sobre un coagulante líquido no disolvente utilizado como colector. Esta técnica puede crear andamios de nanofibras en 3D con mejores propiedades (por ejemplo, porosidad y alta superficie) que las de los andamios tradicionales en 2D producidos por electrospinning estándar. Gracias a estas características, el electrospinning húmedo puede emplearse en una amplia gama de aplicaciones industriales y de ingeniería de tejidos. Esta revisión pretende ampliar el panorama de esta técnica, sus posibles campos de actuación y su gama de materiales habituales. Además, también se discuten sus tendencias futuras. En este estudio, revisamos los artículos sobre este método publicados entre 2017 y 2021 para establecer el estado del arte del electrospinning húmedo y sus aplicaciones más importantes en ingeniería de tejidos cardíacos, cartilaginosos, hepáticos, apósitos para heridas, cutáneos, neuronales, óseos y musculares esqueléticos. Adicionalmente, examinamos sus aplicaciones industriales en la purificación del agua, los filtros de aire, la energía, los sensores biomédicos y los textiles. Los principales resultados de esta revisión indican que los andamios 3D para aplicaciones de ingeniería tisular son biocompatibles; imitan la matriz extracelular (MEC); permiten la viabilidad y diferenciación de las células madre; y tienen una alta porosidad, lo que proporciona una mayor infiltración celular en comparación con los andamios 2D. Por último, descubrimos que, en las aplicaciones industriales del electrospinning húmedo: (1) los aditivos mejoran el rendimiento de los polímeros puros; (2) la concentración de la solución influye en la porosidad y el empaquetamiento de las fibras; (3) la velocidad de flujo, el voltaje y la distancia modifican la morfología de las fibras; (4) la tensión superficial del coagulante no solvente sobre el que se depositan las fibras tiene un efecto sobre su porosidad, compactación y propiedades mecánicas; y (5) el tiempo de deposición define el espesor del andamio

Polymeric Microsensors for Intraoperative Contact Pressure Measurement

Biocompatible sensors have been demonstrated using traditional microfabrication techniques modified for polymer substrates and utilize only materials suitable for implantation or bodily contact. Sensor arrays for the measurement of the load condition of polyethylene spacers in the total knee arthroplasty (TKA) prosthesis have been developed. Arrays of capacitive sensors are used to determine the three-dimensional strain within the polyethylene prosthesis component. Data from these sensors can be used to give researchers a better understanding of component motion, loading, and wear phenomena for a large range of activities. This dissertation demonstrates both analytically and experimentally the fabrication of these sensor arrays using biocompatible polymer substrates and dielectrics while preserving industry-standard microfabrication processing for micron-level resolution. An array of sensors for real-time measurement of pressure profiles is the long-term goal of this research. A custom design using capacitive-based sensors is an excellent selection for such measurement, giving high spatial resolution across the sensing surface and high load resolution for pressures applied normal to that surface while operating at low power

High Precision 3D Printing for Micro to Nano Scale Biomedical and Electronic Devices

Three dimensional printing (3DP), or additive manufacturing, is an exponentially growing process in the fabrication of various technologies with applications in sectors such as electronics, biomedical, pharmaceutical and tissue engineering. Micro and nano scale printing is encouraging the innovation of the aforementioned sectors, due to the ability to control design, material and chemical properties at a highly precise level, which is advantageous in creating a high surface area to volume ratio and altering the overall products’ mechanical and physical properties. In this review, micro/-nano printing technology, mainly related to lithography, inkjet and electrohydrodynamic (EHD) printing and their biomedical and electronic applications will be discussed. The current limitations to micro/-nano printing methods will be examined, covering the difficulty in achieving controlled structures at the miniscule micro and nano scale required for specific applications

Road Surface Feature Extraction and Reconstruction of Laser Point Clouds for Urban Environment

Automakers are developing end-to-end three-dimensional (3D) mapping system for Advanced Driver Assistance Systems (ADAS) and autonomous vehicles (AVs). Using geomatics, artificial intelligence, and SLAM (Simultaneous Localization and Mapping) systems to handle all stages of map creation, sensor calibration and alignment. It is crucial to have a system highly accurate and efficient as it is an essential part of vehicle controls. Such mapping requires significant resources to acquire geographic information (GIS and GPS), optical laser and radar spectroscopy, Lidar, and 3D modeling applications in order to extract roadway features (e.g., lane markings, traffic signs, road-edges) detailed enough to construct a “base map”. To keep this map current, it is necessary to update changes due to occurring events such as construction changes, traffic patterns, or growth of vegetation. The information of the road play a very important factor in road traffic safety and it is essential for for guiding autonomous vehicles (AVs), and prediction of upcoming road situations within AVs. The data size of the map is extensive due to the level of information provided with different sensor modalities for that reason a data optimization and extraction from three-dimensional (3D) mobile laser scanning (MLS) point clouds is presented in this thesis. The research shows the proposed hybrid filter configuration together with the dynamic developed mechanism provides significant reduction of the point cloud data with reduced computational or size constraints. The results obtained in this work are proven by a real-world system