Modeling and Performance Analysis of CSMA-Based JCAS Networks

Joint communication and sensing (JCAS) networks are envisioned as a key enabler for a variety of applications which demand reliable wireless connectivity along with accurate and robust sensing capability. When sensing and communication share the same spectrum, the communication links in the JCAS networks experience interference from both sensing and communication signals. Therefore, it is crucial to analyze the interference caused by the uncoordinated transmission of either sensing or communication signals, so that effective interference mitigation techniques could be put in place. We consider a JCAS network consisting of dual-functional nodes operating in radar and communication modes. To gain access to the shared communication channel, each node follows carrier sense multiple access (CSMA)-based protocol. For this setting, we study the radar and communication performances defined in terms of maximum unambiguous range and aggregated network throughput, respectively. Leveraging on the stochastic geometry approach, we model the interference of the network and derive a closed-form expression for both radar and communication performance metrics. Finally, we verify our analytical results through extensive simulation

Treatment of Spent Pot Lining by Chemical Leaching Using Nitric Acid for Enrichment of Its Fuel Value and Optimzation of The Process Parameters

Over the years numerous methods have been suggested for treatment of Spent Pot Lining (SPL)- a waste produced from aluminum industries that has been declared as hazardous by the US Environmental Protection Agency. In this project chemical leaching treatment method was adopted and several process parameters and their dependency on each other were studied. SPL was subjected to caustic leaching followed by HNO3 leaching at different temperature and liquid to solid ratio combinations. Again an optimized set of values was obtained via Taguchi method. The main objective of the optimization methodology was to determine the effect of acid concentration, alkali concentration, temperature and L/S ratio on the leaching percentage in terms of percentage contribution. Alkali concentration contributed 51.80% in the leaching process, whereas acid concentration contributed only 2.61 %. The maximum leaching percentage was found out to be 50.62% by Taguchi optimization. It was concluded that 2.5 M NaOH, 5 M HNO3 concentration, 4.5 L/S ratio and temperature 75 ±1°C was the best combination for the optimum leaching percentage for final treated SPL. The carbon percentage of SPL was increased from 33.27% to 87.31% as confirmed from the elemental composition obtained by Enegry Dispersive X-ray spectroscopy. Again with the help of existing data, an extensive comparison was made to find out the best suitable acid out of HCl, HNO3, H2SO4 and HClO4 for leaching process keeping L/S ratio constant. It was observed that at normal temperatures H2SO4 gave maximum leaching percentage for all values of alkali concentrations. But as temperature was increased from 25°C to 100°C, the leaching percentage obtained by all acids converged slowly to a constant range

Laser beam welding of commercially pure titanium sheets

In the present work, effect of process parameter such as laser power, welding speed, size of beam diameter on the microstructure and mechanical properties on laser beam welding of annealed commercially pure titanium (cp-ti) grade-2 is investigated.Titanium is preferred due to its wide applications in the field of automobile, marine, aerospace, power plant, structural etc. for its light weight, high specific strength, high corrosion resistance, having good mechanical properties at elevated temperature.Laser welding has more advantages over other normal fusion welding due to its low heat input, high cooling rate and high power density.it provides deeper and narrower weld bead results high welding efficiency and smaller heat affected zone leads to good mechanical property.The laser welding of cp-ti sheet of 1mm thickness was carried out by using a continuous wave (CW) CO2 laser at different operating conditions such as laser power at 2kW & 2.5kW, welding speed from 4m/min to 8m/min and laser intensity distribution by Gaussian Mode (0.18mm beam diameter at focus) and Donut Mode (0.36mm beam diameter at focus).Microstructure of weld size and fusion zone were examined by using optical microscope at different magnifications.Weld size was decreased with increasing welding speed and increased with increasing laser power and spot diameter.At low welding speed, elongated grains were observed in the weld interface. It also showed a sharp interface at large beam diameter (Donut mode). Measurement of micro-hardness was taken across the welding by using micro-hardness testing machine. The Vickers hardness increases from base material to centre of weld region. Tensile testing of the weld was carried out in a universal testing machine and it is observed that tensile strength of weld at different process parameters is approximately equal to the tensile strength of base metal.Comparative studies of process parameters on the laser welding of cp-ti were investigated

Automatic Telephone Answering Machine

An automatic telephone answering machine or system is an electronic device that answers automatically to an incoming telephone call and plays a prerecorded message and is capable of recording a message the caller want to leave. These systems include message recording system having remote acess to message playback, automatic dialing, equipment to receive an alarm, automatic data entry-answering systems and other common telephone devices being used along with modem equipments. The microcontroller typically controls a number of peripherals, components of the answering machine such as an LCD or LED display, an indicator light for recording and playback options, a DTMF receiver and an audio controller. A telephone answering machine must be capble of being remotely activated consisting of: A switch deciding the mode of operation either automatic or normal mode. Provison for receiving the calls automatically when in automatic mode. Provison for recording the message to be deliverd to the incoming user and also to record his mesage Storage for the message Microcontoller to deliver control signal as per the mode of operation Commonly used telephone answering devices comprises of a number of features which allow a user to examine the presence of a call, seize calls, play back recorded voice messages, record an announcement etc. Triggering of a telephone answering machine done by counting the incoming ring signals and when the count surpass a preset number set by the user. The machine is programmed in such a way that if the user does not attain his telephone within a specified time period which is the function of number of ring signals, the call is automaticlly answered and a message is palyed back to the caller as well as asks him to leave a message. KEY WORDS: Answering machine, Answering system, Speech compression, ADPCM, Encoding, Decodin

Evaluation of Amip-Type Atmospheric Fields as Forcing For Mediterranean Sea and Global Ocean Reanalyses

Oceanic reanalyses are powerful products to reconstruct the historical 3D-state of the ocean and related circulation. At present a challenge is to have oceanic reanalyses covering the whole 20th century. This study describes the exercise of comparing available datasets to force Mediterranean Sea and global oceanic reanalyses from 1901 to present. In particular, we compared available atmospheric reanalyses with a set of experiments performed with an atmospheric general circulation model where sea surface temperature (SST) and sea-ice concen- tration are prescribed. These types of experiments have the advantage of covering long time records, at least for the period for which global SST is available, and they can be performed at relatively high horizontal resolutions, a very important requisite for regional oceanic re- analyses. However, they are limited by the intrinsic model biases in representing the mean atmospheric state and its variability. In this study, we show that, within some limits, the atmospheric model performance in representing the basic variables needed for the bulk-formulae to force oceanic data assimilation systems can be comparable to the differences among available atmospheric reanalyses. In the case of the Mediterranean Sea the high horizontal resolution of the set of SST-prescribed experiments combined with their good performance in rep- resenting the surface winds in the area made them the most appropriate atmospheric forcing. On the other hand, in the case of the global ocean, atmospheric reanalyses have been proven to be still preferable due to the better representation of spatial and temporal variability of surface winds and radiative fluxes. Because of their intrinsic limitations AMIP experiments cannot provide atmospheric fields alterna- tive to atmospheric reanalyses. Nevertheless, here we show how in the specific case of the Mediterranean Sea, they can be of use, if not preferable, to available atmospheric reanalyses

The complex structure of Fomes fomentarius represents an architectural design for high-performance ultralightweight materials

We thank C. Li from the Max Planck Institute of Colloids and Interfaces in Potsdam, Germany, for help during synchrotron measurements at the μSpot beamline at BESSY at the Helmholtz-Zentrum Berlin für Materialien und Energie in Berlin, Germany. We acknowledge the provision of facilities and technical support by Aalto University at the OtaNano Nanomicroscopy Center (Aalto-NMC). This work was supported by the Academy of Finland project 348628, the Jenny and Antti Wihuri Foundation (Centre for Young Synbio Scientists), and the Academy of Finland Center of Excellence Program (2022–2029) in Life-Inspired Hybrid Materials (LIBER) project number 346106, and by internal funding from the VTT Technical Research Center of Finland Ltd. We also acknowledge the Dutch Research Council (NWO, domain Applied and Engineering Sciences: MYCOAT project number 18425) and the Horizon 2020 programs of the European Union (FUNGAR; project 58132 and iNEXT-Discovery, project 871037) for NMR studies. Furthermore, the high-field NMR experiments were supported by uNMR-NL, the National Roadmap Large-Scale NMR Facility of the Netherlands (NWO grant 184.032.207), and the uNMR-NL grid (NWO grant 184.035.002).High strength, hardness, and fracture toughness are mechanical properties that are not commonly associated with the fleshy body of a fungus. Here, we show with detailed structural, chemical, and mechanical characterization that Fomes fomentarius is an exception, and its architectural design is a source of inspiration for an emerging class of ultralightweight high-performance materials. Our findings reveal that F. fomentarius is a functionally graded material with three distinct layers that undergo multiscale hierarchical self-assembly. Mycelium is the primary component in all layers. However, in each layer, mycelium exhibits a very distinct microstructure with unique preferential orientation, aspect ratio, density, and branch length. We also show that an extracellular matrix acts as a reinforcing adhesive that differs in each layer in terms of quantity, polymeric content, and interconnectivity. These findings demonstrate how the synergistic interplay of the aforementioned features results in distinct mechanical properties for each layer.Peer reviewe