Average Transfer Research Articles

Time-Frequency-Space EEG Decoding Model Based on Dense Graph Convolutional Network for Stroke.

Stroke, a sudden cerebrovascular ailment resulting from brain tissue damage, has prompted the use of motor imagery (MI)-based Brain-Computer Interface (BCI) systems in stroke rehabilitation. However, analyzing EEG signals from stroke patients is challenging because of their low signal-to-noise ratio and high variability. Therefore, we propose a novel approach that combines the modified S-transform (MST) and a dense graph convolutional network (DenseGCN) algorithm to enhance the MI-BCI performance across time, frequency, and space domains. MST is a time-frequency analysis method that efficiently concentrates energy in EEG signals, while DenseGCN is a deep learning model that uses EEG feature maps from each layer as inputs for subsequent layers, facilitating feature reuse and hyper-parameters optimization. Our approach outperforms conventional networks, achieving a peak classification accuracy of 90.22% and an average information transfer rate (ITR) of 68.52 bits per minute. Moreover, we conduct an in-depth analysis of the event-related desynchronization/event-related synchronization (ERD/ERS) phenomenon in the deep-level EEG features of stroke patients. Our experimental results confirm the feasibility and efficacy of the proposed approach for MI-BCI rehabilitation systems.

CFD Study on Heat Transfer in Hybrid Nanofluid with Coil Controller in Double Tube Heat Exchanger

Abstract: Heat exchanger that heats up to two or more processing fluids. Heat exchangers have a range of domestic and commercial applications. Use in steam plants, manufacturing plants, heat and air conditioning facilities, transportation, and cooling systems. Through analysis, Ordinarily, the presence of Cu+Al2O3 nanoparticles in the base fluid increases the properties of convective heat transfer and is thus more efficient than Al2O3 nanoparticles (at a steady concentration of volume). The findings revealed that the average heat transfer coefficient increases in line with the Reynolds number. Analysis has shown that the average thermal transfer coefficient value for hybrid nanofluid is 12 percent greater than the average for a single nanofluid. In the case of hybrid nanofluid compared to Mono nanofluid, the value of Nusselt is 18 per cent higher.

Intensification of the rate of heat and mass transfer at the wall of a stirred tank reactor by integrating a helical coil turbulence promoter with the tank wall

ABSTRACT The influence of a helical coil turbulence promoter on liquid-solid mass transfer rates in a stirred tank was investigated using a technique that involved measuring the rate of diffusion-controlled copper dissolution in acidified dichromate. The study examined the effects of helical coil tube diameter (d), helical coil pitch (p), impeller rotation speed, impeller geometry (axial and radial), the presence of baffles, and solution physical properties. The presence of the helical coil near the reactor wall significantly enhanced mass transfer rates, with a factor ranging from 1.01 to 2.48. This improvement was accompanied by a corresponding increase in the volumetric mass transfer coefficient (kA), ranging from 2.68 to 4.55, depending on operating conditions. Further analysis revealed that the average mass transfer coefficient increased with decreasing coil tube diameter, while coil pitch had a minimal impact. Additionally, radial flow turbines demonstrated superior mass transfer performance compared to axial flow turbines. The presence of baffles also promoted higher mass transfer rates compared to unbaffled reactors. The experimental data were successfully correlated using dimensionless correlations, emphasizing the significance of these correlations in scaleup and design optimization of catalytic stirred tank reactors with efficient cooling systems.

Radioactivity levels, soil-to-grass and grass-to-milk transfer factor of natural radionuclides from grazing area in Erbil governorate, Iraq

The levels of naturally occurring radionuclides in soil, grass, and milk were measured in this study in order to calculate the transfer factor of radionuclides from soil to grass and grass to milk obtained from Erbil governorate in Iraq. High efficiency gamma spectrometry used for the measurement. It has been determined that the mean activity concentrations of 232Th, 226Ra, and 40K are 3.08, 8.37, and 253 BqKg−1 in soil, 0.5, 0.39, and 203.05 BqKg−1, in grass, and 0.29, 0.084, and 29.69 BqL−1, in milk, respectively. For soil to grass, the transfer factor values for 232Th, 226Ra, and 40K were found to be 0.18, 0.052, and 0.84, respectively, for soil to grass. For grass to milk, the transfer factor values for 232Th, 226Ra, and 40K were found to be 0.45, 0.166, and 0.11 dayL−1, respectively. The average transfer factor for 232Th, 226Ra, and 40K in all samples were lower than the world average value.

Assessment and health risk of fluoride from Northeast Indian tea (Camellia sinensis L.): Fixing up the maximum residue level of fluoride in tea

The tea plant is considered a strong fluoride (F-) hyperaccumulator plant. We have proposed the Maximum Residue Limit (MRL) of F- in tea based on 321 tea samples collected from 8 tea-growing regions of Northeast India. Total F- as well as water-soluble F- content was analysed through the ion selective electrode with the recovery percentage of 100–108 to ascertain the risk associated with F- towards human health. It has been observed that total F- contents (mg kg−1) in Cachar, Darjeeling, Dooars, North Bank, South Bank, Terai, Tripura, and Upper Assam ranged from 42.5 to 111.5, 16.0 to 168.0, 48.0 to 291.0, 36.5 to 314.0, 60.0 to 154.0, 26.5 to 233.5, 26 to 118 and 44 to 244, respectively. The F- content in tea infusion varied between 1.08 mg L−1 and 2.43 mg L−1 across all eight regions with a mean of 1.90 mg L−1. The average transfer of F- from made tea (processed young shoot of tea plants comprising a bud and 2 to 3 leaves) to tea infusion was 100.46%. Fluoride content in infusion was decreased with the increment of infusion number but increased gradually with continuous infusion time. The non-carcinogenic health risk was assessed. Calculated Hazard Quotient values were far below 1. The calculated and rounded MRL (300 mg kg−1) was recommended for F- in tea in India.

Controlled dynamic variation of interfacial electronic and optical properties of lithium intercalated ZrO2/MoS2 vdW heterostructure

Efficient strategies for modifying the characteristics of van der Waals (vdW) layered materials in a precise and reversible mode remain challenging. Our suggested method for customization entails the implementation of layer-sliding and intercalation. In this work, a norm-conserving approach within the context of density functional theory has been used to examine the electronic and optical properties of two-dimensional (2D) van der Waals heterostructure (vdWHS), which is modeled by using 2D zirconium dioxide (1T-ZrO2) and molybdenum disulfide (1T-MoS2) monolayers of similar phase. Both contributing monolayers have similar lattice structures, with a minimum lattice mismatch of 0.83 %, and have corrugation on both sides that can successfully retain foreign species at the vdW-gap. In the next step, interfacial engineering through Li-intercalation and layer-sliding was employed to modify physical properties of the vdWHS. It is the worth mentioning that a narrow bandgap of 0.102 eV (0.22 eV) has been observed in the unintercalated ZrO2/MoS2 vdWHS when employing PW-LDA (hybrid-functional). Li-intercalation and sliding process significantly influenced the electronic properties of the studied vdWHS. Furthermore, un-slided and fully-slided Li-intercalated vdWHS exhibit an increase in the vdW-gap by 3.78 % and 27.14 %, respectively, as compared to unintercalated vdWHS. To further understand the electrical behaviour at the interface of contributing monolayers, a comparative study has also been made for the variation in the planar average charge density difference, charge transfer, and interface dipole moment for unintercalated and intercalated vdWHS. In the unintercalated vdWHS, the calculated values of ΔQ and μ(z) provide evidence of significant charge transfer from 1T-ZrO2 to 1T-MoS2 before sliding, whereas in the fully-slided vdWHS, there is 80.11 % more charge transfer from 1T-MoS2 to 1T-ZrO2. Li-intercalation increases the magnitude of ΔQ (by 90.27 %) near 1T-MoS2, indicating a sufficient quantity of charge transfer from the 1T-MoS2 monolayer. The results of the anisotropic analysis show that the calculated in-plane and out-of-plane components of the real and imaginary parts of the dielectric function differ significantly. The optical absorption and energy losses of Li-intercalated vdWHS experience a substantial decrease of about 90 % and 50 %, respectively, as compared to unintercalated vdWHS. Our employed method promotes the notion that interfacial engineering through simultaneous layer-sliding and intercalation approach can be used to regulate and modify the physical properties of 2D insulator/metal based vdWHS.

Turbulent energy transfers in physical and scale spaces at dissipative length scales

In statistically stationary homogeneous incompressible turbulence, the average energy transfer rate balance which exists at diffusion/dissipation-dominated length scales does not reflect what actually happens locally in space and time. We use a highly resolved direct numerical simulation of forced periodic turbulence to shed some light on the actual fluctuating dynamics which occur at these very small scales and which are rubbed off by averaging. Even though the viscous diffusion in physical space averages to zero and fluctuates less intensely than all other terms (except the energy input rate) in the local (in space–time) two-point energy balance, it fundamentally cannot be neglected. The local unsteadiness and the interspace turbulence transport terms cannot be ignored either in the interscale energy dynamics in spite of the fact that they also average to zero.

A cost-effective and high-efficient EV shared fast charging scheme with hierarchical coordinated operation strategy for addressing difficult-to-charge issue in old residential communities

Charging infrastructures are being deployed widely in urban and rural areas to solve the so-called “last one-kilometer” charging problem. However, for old residential communities, the existing difficult-to-charge issue is not easily solved solely by the widespread deployment of charging infrastructure owing to limited spaces, complex reconstruction, and huge costs. In this context, this paper introduces a cost-effective and high-efficient shared fast charging scheme for old residential communities. The comprised registration-based queuing charging mechanism is proposed to schedule electric vehicle (EV) charging. An integrated and multi-stage power electronic device called smart interlinking unit (SIU) is introduced for grid reconstruction. The SIU-based charging station architecture features flexible control capability, enabling DC power supply for terminal EV chargers. For this architecture, a novel hierarchical coordinated operation strategy is designed, comprising the upper-level real-time vehicle-to-grid (V2G) dispatching and lower-level coordination strategies. Case studies demonstrate that the proposed scheme could accommodate 40 % EV penetration, while exhibiting a significant decline in system investment and occupied area compared to the slow charging scheme. Additionally, a 1.3 % improvement in average transfer efficiency is verified under this architecture. The proposed strategy is proven to realize a prominent power peak-shaving and valley-filling, effective transformer load balance, and DC voltage restoration.

Research on the scheduling method of ground resource under uncertain arrival time

We present a two-stage scheduling approach including proactive and reactive scheduling to solve the ground resource scheduling problem with uncertain arrival time. In the first stage, an integer programming model is constructed to minimize the delay and transfer costs. After solving this model, we obtain a baseline scheduling plan that considers the service arrival time uncertainty. In the second stage, the feasibility of the subsequent benchmark plan is evaluated based on the current state of the services and resources. The reactive scheduling model is enabled when trigger conditions are met. Moreover, an improved adaptive large neighborhood search is designed to solve the proactive scheduling model effectively. Real data from an international airport in South China is used as a test case to compare different scheduling strategies. The results show that it is difficult to handle the uncertainty of the problem with the benchmark plan that simply considered buffer time. Compared with rolling time-domain scheduling, the average transfer cost of the scheduling strategy proposed in this paper increased slightly, but the average service delay cost can be reduced significantly. Algorithm-wise, instances of different scales are designed to verify the effectiveness of the improved adaptive large neighborhood search algorithm. The efficiency of the algorithm scheme is better than that of the Gurobi solver scheme in medium to large-scale problems. Therefore, the forward and reactive strategies can better handle the uncertainty of airport ground protection services as they can simultaneously guide the allocation and utilization of airport ground protection resources.

Closed-Form Dynamic Modeling and Performance Evaluation of a 4-Degrees-of-Freedom Parallel Driving Mechanism

Abstract Kinematic estimations and dynamic performance assessments are fundamental theoretical issues to realize the mechanism from conceptual design to engineering application. In this article, the closed-form dynamic formulations of a 4-degrees-of-freedom (DoFs) parallel driving mechanism are derived by combining the Lagrange method and the virtual work principle. The selection principle of generalized coordinates and the steps for inverse dynamics modeling of the manipulator are proposed. Simulation results verify the correctness of the dynamic model, and a physical prototype has been built. Based on the dynamic modeling, the concise algebraic expression of the operational space inertia matrix of the parallel driving mechanism is deduced. Because the translation and rotation degrees-of-freedom are inconsistent in the operational space, the Jacobian matrix is adopted to map the inertia matrix from the operational space to the joint space. Based on the inertia matrix in joint space, the average energy transfer efficiency (AETE) index is proposed. Finally, two control techniques for the manipulator implementable in joint space are compared. The AETE index and dynamic modeling method suggested in this article can be further used in other manipulators for dynamic analysis and motion system design.

Flow characteristics analysis and performance evaluation of a novel rotary proton exchange membrane fuel cell

This paper proposes a new type of rotary proton exchange membrane fuel cell (R-PEMFC) and its simulation model is established and verified based on experimental data. Then the effects of different rotational angular speeds (RASs) on reactant flow characteristics and electrochemical reactions are investigated. Also, the key quantitative indexes, such as average value, uniformity index and effective mass transfer coefficient (EMTC) are adopted, while combining the polarization curve and net power to estimate the comprehensive R-PEMFC performance. The results indicate that the R-PEMFC effectively ameliorates uneven distribution and improves the transmission capability and output performance. Compared with the static state (0 rpm), the EMTC and maximum power density are enhanced by 65.86 % and 8.51 % respectively at the RAS of 1080 rpm, and the net power density can reach 5316 W·m−2.

Investigation on the Metal Transfer and Cavity Evolution during Submerged Arc Welding with X-ray Imaging Technology

The physical phenomena of submerged arc welding (SAW) conducted with a 1.6 mm flux-cored wire were investigated using X-ray imaging technique. Three kinds of metal transfer modes were confirmed in this paper, namely the front flux wall-guided droplet transfer, back flux wall-guided droplet transfer, and repelled droplet transfer, of which the corresponding percentages were 47.65%, 45.29%, and 7.06%, respectively. Although the average sizes of the droplets for SAW and FCAW (flux-cored wire welding) were 2.0 mm and 1.9 mm with an average droplet transfer time of 90.3 ms, it required 36.4% more time for the droplet of SAW to finish one metal transfer than it did in FCAW. In addition, the volume of the cavity was not constant but repeated a cycle mode of “expansion and contraction” during the whole process. Thus, the dynamics of the cavity and viscous resistance caused by the flux collectively slowed down the velocity of the droplets from the wire to the weld pool in SAW. Compared with FCAW, a smoother weld without pits and pores was manufactured during the SAW process. Due to the compression effect of the flux, the 14.5 mm average weld width of SAW was 2.9 mm shorter than that of the FCAW. Furthermore, the thickness of slag with a porous structure in SAW was 2.7 times of that in FCAW, indicating that it could provide better protection to the weld of SAW.

Cross Contamination during Simulated Food Pantry Handling of Apples, Oranges and Potatoes

Food pantries receive, store, distribute and serve food to hundreds of people throughout a community. Safe food handling during all these activities is of paramount importance or food may support growth of pathogens and result in foodborne illnesses after consumption. Year round, and more frequently during holiday seasons, food pantries are seeking food donations to support people in need. Since most food pantries products are donated, the safety of these products from a health perspective can be tricky. The quality of food donations coupled with the way food is handled in these facilities can pose major safety concerns. To determine the potential for transfer of bacteria during handling of food at food pantries, apples, potatoes and oranges were inoculated with a non-pathogenic, fluorescently-labeled strain of Escherichia coli, then handled with gloved hands after which another non-inoculated apple, potato or orange was handled. E. coli was then enumerated from each piece of food and gloves to determine the transfer rate from the inoculated piece of food to gloves and the non-inoculated food. The average transfer rate from the inoculated food to gloves was 36.4%, from glove to un-inoculated food was 42.4% and from the inoculated food to un-inoculated food was 15.2%. Whether it be from surfaces or hands, cross-contamination of food and surfaces can readily occur and can result in increased likelihood of illness unless proper hygiene is employed. Food pantries can reduce the likelihood of microbial cross-contamination using proper handwashing techniques, and sanitation of surfaces and utensils. Proper hygiene is critical for food pantries to reduce the likelihood of bacterial transfer to previously uncontaminated surfaces.

Feasibility of Establishing a Stroke Care System through the Acute Stroke Hotline in Busan Metropolitan Area

Background: The importance of establishing a regional stroke safety net for the treatment of acute stroke is increasingly emphasized. In this study, we analyzed effectiveness of transferring the suspected acute ischemic stroke (AIS) patients through the 1899-0215 hotline system from 119 ambulances and nearby hospitals.Methods: From July 2015 to July 2022, we analyzed data from 632 suspected acute stroke patients through the hotline. Furthermore, we investigated the proportion of patients in the target population who were eligible for reperfusion therapy and compared cases transferred by 119 emergency services (EMS) with those transferred from nearby hospitals.Results: Six hundred thirty-two suspected acute stroke patients were transferred to our stroke center through the 1899-0215 hotline system. The accuracy of diagnosing acute stroke among transferred patients is 81.0% for 119 EMS and 80.5% for cases transferred from nearby hospitals. Of the 200 patients transferred from hospitals, they were transferred from 47 nearby hospitals with an average transfer distance of 38.2 km and an average transfer time of 65 minutes. Among 291 patients diagnosed with AIS, The onset-to-door time was significantly shorter (<i>p</i><0.01) for patients transferred by 119 EMS. The proportion of patients who received reperfusion therapy was significantly higher (<i>p</i><0.01) for those transferred by 119 EMS.Conclusions: The hotline service will become a useful tool for establishing a regional stroke network in the Busan area, and its effectiveness will be particularly useful for 119 EMS. Measures are needed in the Busan metropolitan region to ensure the speediness of transferring acute stroke patients between hospitals.

Lipid composition and properties affect protein-mediated carotenoid uptake efficiency from membranes

Carotenoids are pigments of diverse functions ranging from coloration over light-harvesting to photoprotection. Yet, the number of carotenoid-binding proteins, which mobilize these pigments in physiological media, is limited, and the mechanisms of carotenoid mobilization are still not well understood. The same applies for the determinants of carotenoid uptake from membranes into carotenoproteins, especially regarding the dependence on the chemical properties of membrane lipids. Here, we investigate xanthophyll uptake capacity and kinetics of a paradigmatic carotenoid-binding protein, the homolog of the Orange Carotenoid Protein's C-terminal domain from Anabaena sp. PCC 7120 (AnaCTDH), using liposomes formed from defined lipid species and loaded with canthaxanthin (CAN) and echinenone (ECN), respectively. Phospholipids with different chain length and degree of saturation were investigated. The composition of carotenoid-loaded liposomes directly affected the incorporation yield and storage ratio of CAN and ECN as well as the rate of carotenoid uptake by AnaCTDH. Generally, saturated PC lipids were identified as unsuitable, and a high phase transition temperature of the lipids negatively affected the carotenoid incorporation and storage yield. For efficient carotenoid transfer, the velocity increases with increasing chain length or membrane thickness. An average transfer yield of 93 % and 43 % were obtained for the formation of AnaCTDH(CAN) and AnaCTDH(ECN) holoproteins, respectively. In summary, the most suitable lipids for the formation of AnaCTDH(CAN/ECN) holoproteins by carotenoid transfer from artificial liposomes are phosphatidylcholine (18:1) and phosphatidylglycerol (14:0). Thus, these two lipids provide the best conditions for further investigation of lipid-protein interaction and the carotenoid uptake process.

Investigation on the role of the finger Transfer Function in tactile rendering by Friction-Induced-Vibrations

The world of haptics, tactile rendering of textures and tactile interfaces has witnessed significant expansion in the last years. When dealing with the design of tactile devices, the interaction between the device and the user's finger becomes crucial. With a focus on optimizing vibrotactile devices for texture rendering, a parametric analysis of the dynamic transfer function of the human finger was conducted under different test conditions. Discrimination campaigns have been conducted, exploiting an average transfer function among participants, to simulate surface textures by Friction-Induced Vibrations. The excellent results of the discrimination campaigns evidenced the effectiveness of the approach, allowing to get rid of the need to characterize the specific finger Transfer Function for each user of the vibrotactile device.

Key mechanisms and process features of the metal transfer and cavity evolution during underwater submerged arc welding

The key mechanisms and process features of the inner physical processes and quality improvement for the novel underwater submerged arc welding (USAW) were revealed with the employment of X-ray observation. Based on the investigation of metal transfer, cavity, and behaviors of the weld pool and flux in USAW, three kinds of droplet transfer mode were confirmed, namely the indirect transfer, direct transfer, and surface tension transfer, and the proportions of them were 81.8%,12.9% and 5.3%, respectively. Compared with underwater wet welding (UWW), the average droplet transfer period was greatly reduced from 198.5 ms to 102.8 ms, and the mean sizes were also decreased from 3.2 mm to 2.2 mm in USAW. Because far more gases were generated in USAW (4394.2 ml/min) than in UWW (755.7 ml/min), the leading gas flow dragging force acting on the droplet was much stronger in USAW, which repelled the smaller droplet to detach from the wire tip within shorter time than it did in UWW. In addition, smooth and uniform weld seam without obvious defects was produced by USAW, of which the width and reinforcement were increased and reduced by 22% and 14%, respectively. And the 4.6 mm thickness of heat-affected zone for the joint of USAW was 59% wider than that of the UWW joint, indicating the cooling rate was effectively reduced in USAW, which consequently help acquiring sound quality joints in underwater welding.

Achieving controllable multifunctionality through layer sliding

Dynamical variation of physical properties in a controllable fashion provides exciting possibilities to obtain multifunctional materials. In this work, layer-sliding is employed to modify the structural, interfacial electronic and optical properties of unintercalated and Mg-intercalated two-dimensional (2D) van der Waals heterostructure (vdW-HS) consisting of buckled silicene and hexagonal boron nitride (hBN). The most stable stacking configuration of silicene over hBN is screened out and then intercalated with Mg at the interface. Dynamical-dependent changes in the properties of vdW-HS are performed by sliding silicene over hBN monolayer in the absence and presence of the intercalant. Layer-sliding is carried out in equal length intervals, and various parametric quantities related to the physical characteristics of the vdW-HS are repeatedly calculated and compared. Apart from various parametric quantities, stability of unintercalated and Mg-intercalated vdW-HS is also checked by means of relative total energies, binding energies and vdW gaps along the sliding pathway. Comparison of binding energies shows that the un-slided, half-slided, and fully-slided Mg-intercalated vdW-HS are 1.52, 1.44 and 1.42 eV more stable than the unintercalated vdW-HS. Opening of a small band gap of 12, 31 and 28 meV for un-slided, half-slided and fully-slided unintercalated vdW-HS, respectively, is worth mentioning. To study the interfacial electronic behavior, planar average charge density difference (Δρ) and charge transfer (ΔQ) are also calculated and varied via layer-sliding. Further, we calculated diverse optical spectra such as the complex dielectric function (DF), electron energy loss function [L(ω)], diagonal components of dielectric tensor [ε(iω)], refractive index [n(ω)], extinction coefficient [k(ω)], absorption coefficient [α(ω)], and reflectivity [R(ω)] for un-slided, half-slided and fully-slided unintercalated and Mg-intercalated vdW-HS. Interestingly, the polarization and energy losses have been reduced in the case of Mg-intercalated vdW-HS. The suggested layer-sliding method can be established as a general scheme for bringing multifunctionality into a layered material.

Analysis of data from the full-scale prototype testing of the WASP – A novel wave measuring buoy.

To assess the viability of locations for wave energy farms, and design effective coastal protection measures, knowledge of local wave regimes is required. Current regime-measuring devices are expensive, and the aim of the WASP Project is to develop a low-cost, self-powering wave-measuring device. The Wave-Activated Sensor Power Buoy (WASP) comprises a floating body with a moonpool. The relative motion of the water level in the moonpool to the buoy will pressurise and depressurise the air above the water column, which will be used to drive a bidirectional turbine in the manner of an oscillating water column, which will operate in conjunction with a generator to recharge an on-board battery pack. It has previously been demonstrated through tank testing of scale-models that a sea-state may be estimated from measurements of the pressure within the air above the water column under controlled conditions [1]. Important statistical parameters relating to the sea state, such as the significant wave height, zero-cross period et cetera. may then be estimated from the spectral moments of the wave spectrum [2].
 This paper seeks to validate the use of measurements taken of the pressure in a volume of air contained in a chamber above an oscillating water column (OWC) (which is in communication with the ocean) to estimate the sea state which induces motion of the water column.
 The WASP was deployed from March to July 2019 at the Smart Bay test facility in Galway Bay, Ireland. The ¼ Scale test site was previously characterised by B Cahill UCC 2011 [3] using data captured by the Marine Institute Datawell WaveRider buoy from 2006 to 2011. Pressure signal data recorded by the WASP at a frequency of 8Hz was processed in to 30-minutes blocks to reflect the presented data from the WaveRider buoy, from which the WASP was moored a distance of 400m from during deployment. Power Density Spectra for 6,500 thirty-minute sea states were generated and an inverse transfer function between the WASP and the WaveRider produced. This allowed for the calculation of the associated significant wave height, Hs, and zero-crossing period, Tz, from the WASP pressure data for each thirty-minute block of data. At this time, outliers and bimodal spectra were removed to simplify the analysis, and the data was binned based on Hs and Tz ranges. For each bin, average inverse transfer functions were generated. A Bretschneider Spectrum [4] was produced using the Hs and Tz values from the WaveRider data for the respective binned WASP data. An average transfer function was then generated between the Bretschneider models and the corresponding sea states for the WASP. Using this final transfer function, a scatter plot of Hs and Tz for the test site was generated and compared against the previously produced scatter plot from the initial resource characterisation of the Galway Bay Test Site in 2011 in order to determine if the WASP is capable of measuring sea-states through measurement of time series pressure signals in the volume of air above the water column in the OWC.

Transmission Timing Control among Both Aperiodic and Periodic Flows for Reliable Transfer by Restricted Packet Loss and within Permissible Delay in Wireless Sensor Networks

Nowadays, in various wireless sensor networks, both aperiodically generated packets like event detections and periodically generated ones for environmental, machinery, vital monitoring, etc. are transferred. Thus, packet loss caused by collision should be suppressed among aperiodic and periodic packets. In addition, some packets for wireless applications such as factory IoT must be transferred within permissible end-to-end delays, in addition to improving packet loss. In this paper, we propose transmission timing control of both aperiodic and periodic packets at an upper layer of medium access control (MAC). First, to suppress packet loss caused by collision, transmission timings of aperiodic and periodic packets are distributed on the time axis. Then, transmission timings of delay-bounded packets with permissible delays are assigned within the bounded periods so that transfer within their permissible delays is possible to maximally satisfy their permissible delays. Such control at an upper layer has advantages of no modification to the MAC layer standardized by IEEE 802.11, 802.15.4, etc. and low sensor node cost, whereas existing approaches at the MAC layer rely on MAC modifications and time synchronization among all sensor nodes. Performance evaluation verifies that the proposed transmission timing control improves packet loss rate regardless of the presence or absence of packet's periodicity and permissible delay, and restricts average transfer delay of delay-bounded packets within their permissible delays comparably to a greedy approach that transmits delay-bounded packets to the MAC layer immediately when they are generated at an upper layer.