Peripheral photoplethysmography variability analysis of sepsis patients

Sepsis is associated with impairment in autonomic regulatory function. This work investigates the application of heart rate and photoplethysmogram (PPG) waveform variability analysis in differentiating two categories of sepsis, namely systemic inflammatory response syndrome (SIRS) and severe sepsis. Electrocardiogram-derived heart period (RRi) and PPG waveforms, measured from fingertips (Fin-PPG) and earlobes (Ear-PPG), of Emergency Department sepsis patients (n = 28) with different disease severity, were analysed by spectral technique, and were compared to control subjects (n = 10) in supine and 80° head-up tilted positions. Analysis of covariance (ANCOVA) was applied to adjust for the confounding factor of age. Low-frequency (LF, 0.04-0.15 Hz), mid-frequency (MF, 0.09-0.15 Hz) and high-frequency (HF, 0.15-0.60 Hz) powers were computed. The normalised MF power in Ear-PPG (MFnu Ear) was significantly reduced in severe sepsis patients with hyperlactataemia (lactate > 2 mmol/l), compared to SIRS patients (P 0.05), suggesting that there may be a link between 0.1 Hz ear blood flow oscillation and tissue metabolic changes in sepsis, in addition to autonomic factors. The study highlighted the value of PPG spectral analysis in the non-invasive assessment of peripheral vascular regulation in sepsis patients, with potential implications in monitoring the progression of sepsis

Sloshing in a closed domain under unidirectional excitation

1145-1153Sloshing is a phenomenon where a partially filled tank is exerted into various environmental sea conditions, such as wave and wind. Sloshing in a tank of liquefied natural gas carrier can lead to structural damage of tank structures and motion instability of the carrier. Thus, sloshing analysis needs to be conducted beforehand to minimize the risk of damages. This paper presents experimental and numerical study on sloshing phenomenon in a prismatic membrane tank model under unidirectional excitation with 30% water filling condition. A regular wave motion stimulated by the linear actuator was applied to the model tank and recorded by a video camera. Meanwhile, OpenFoam software was used to simulate the sloshing numerically in a volume of fluid method based on Navier-Stokes theorem. The sloshing patterns and free surface elevation in the prismatic membrane model tank, with the same input amplitude and frequency, were investigated for both cases. Both experimental and simulation results showed reasonable agreement on the sloshing profile, while the internal free surface elevation in the closed domain indicated a deviation with maximum absolute error of 4.9 cm

AFC motor control using low cost and mobile data acquisition system with dsPIC30 microcontroller and Lubin Kerhuel blockset for MATLAB/Simulink

Data acquisition system (DAQ) plays an important role in research activities. Commercially available DAQ can be expensive and most are PC based and can be overly equipped for the task at hand. This paper proposes a low cost and mobile DAQ system with a dsPIC30 microcontroller form Microchip and program using Lubin Kerhuel Blockset for MATLAB/Simulink. An experimental rig consisting of a Maxon motor equipped with an Escon motor driver connected to a dsPIC30F3014 microcontroller was developed to demonstrate the potential of the proposed system. AFC was used as the control system and result from the experimental setup was presented in MATLAB/Simulink. Results clearly imply the viability of the proposed setu

Parametric resonance avoidance of offshore crane cable in subsea lowering operation through A* heuristic planner

2422-2433Parametric resonance of offshore crane cable was predicted by using Mathieu equation to provide structural safety prediction during subsea lowering operation. This paper studied the predicting method and automatic resonance avoidance of offshore crane cable to complement the safety management during subsea lowering operation. The offshore crane cable was modeled as a tensioned long cylindrical structure and Mathieu instability coefficients were utilized to predict the dynamic instability of the structure. Numerical analyses were conducted to predict the parametric resonance of cable, evaluate the sensitivity of effective submerged length, dynamic tension variation, and plan for resonance avoidance mechanism automatically. Dynamic instability at sub-harmonic 2:1 unstable region of Mathieu stability diagram potentially creates high risk for lowering operation if the damping coefficient is low. Dynamic tension variation can cause instability of offshore crane cable during passing through wave splash zone and landing subsea payload. The reduction of axial tension variation can stabilize the dynamic of offshore crane cable. Parametric resonance of cable is also sensitive to the total payload. The findings of this paper can enhance structural integrity prediction of offshore crane cable and provide an automatic planner to the operator to avoid parametric resonance during subsea lowering operation

Algorithm to detect roundabout environments for mobile robot based on laser range finder and camera

This research is aimed towards developing an algorithm for detecting road roundabout environments and estimating the collision free-path. Laser range finder (LRF) and camera are combined together to detect the mini-roundabout environments that are developed and built in a laboratory setting. The signal processing of the LRF is accomplished in MATLAB environment using the proposed algorithm to determine the road curbs and find the current position of the mobile robot within the environments. The video processing is performed also in MATLAB to identify the roundabout center when it is detected. The experiments are performed using the developed experimental setup and the data are processed in real-time. The results demonstrate the capability of the algorithm to effectively recognize the roundabout environment

Hydrodynamic sloshing of microalgae in membrane type photobioreactor

The tropical climate, wide diversity of microalgae species, long coastline, abundant sources of agriculture effluent, and active phycology research are key factors that drives Malaysia to be highly competitive in the global microalgae market. Microalgae are vital in a variety of applications such as: biofuel, health foods, agricultural feeds and chemical extractions. However, mass cultivation of microalgae is still not cost effective in Malaysia due to huge energy consumption Therefore, cultivation of microalgae that utilizes wide ocean space and wave energy for mixing has gained interest since it has considerably lower production cost. Nonetheless, the effects of ocean wave-induced sloshing in terms of its efficiency of mixing have not been fully researched. Thus, this study has been conducted to investigate the effects of sloshing hydrodynamics in microalgae cultivation by studying the interactions of sloshing hydrodynamics and mixing efficiency inside a floating photobioreactor. A membrane type photobioreactor has been used to slosh microalgae culture on its free surface. The result of mixing efficiency for suspended solid particles in liquid is the main concern. Experiments in unidirectional excitation proven that mixing rate of solid-liquid medium is dependent on the excitation amplitude, excitation frequency and filling ratio, where mixing rate is highest at 30% filling ratio with increasing excitation amplitude and excitation frequency. With deeper comprehension on the interaction effects of sloshing hydrodynamics and mixing efficiency, upscaling of novel microalgae cultivation method in industrial size can be expected

Microalgae cultivation in offshore floating photobioreactor: State-of-the-art, opportunities and challenges

The wide application of microalgae in health foods, nutritional feeds, aquaculture, pharmaceutical extracts, and biofuel production, has brought about the advancement of the microalgae cultivation industry. However, commercial-scale cultivation of microalgae still faces one major challenge, which is its economic feasibility, with lower cost and energy consumption. Developing floating photobioreactors to be utilized in offshore open water areas has gained more interest recently as it can diminish the cost effects of onshore land utilization, while seeking for additional benefits, such as regulated temperature, proximity to sunlight and nutrient supplies, and integrated ocean renewable energy. Thereby, this is timely to explore the potential of floating photobioreactors for microalgae cultivation in the offshore region. This review deliberately presents the characteristics of offshore environments and their potential effects on microalgae cultivation, as factors such as location selection, heat capacity, and utilization of cultivation resources are significantly different from conventional land-based cultivation. Compared to land-based photobioreactors, the design of floating photobioreactors has the opportunity to adopt hydrodynamical design, by utilizing the external force from ocean waves to generate internal liquid sloshing for improving the mixing of cultivation medium. While offshore-based microalgae cultivation is considerably new as part of blue economy and mariculture, this review provides insights into the opportunities for further advancement of offshore microalgae cultivation technologies. The encouraging factors for hybridization of offshore microalgae cultivation include mariculture, carbon dioxide capture and utilization, hydrogen production, and ocean thermal energy. Such understandings are vital to improving microalgae cultivation in offshore floating photobioreactors towards a valuable alternative to the current concerns in developing commercial scale of the microalgae industry. Various challenges in biological issues, economic and environmental challenges, installation and maintenance, as well as destructive hydrodynamic loads are also discussed