Highly Stretchable Conducting SIBS-P3HT Fibers

Poly(styrene-β-isobutylene-β-styrene)-poly(3-hexylthiophene) (SIBS-P3HT) conducting composite fibers are successfully produced using a continuous flow approach. Composite fibers are stiffer than SIBS fibers and able to withstand strains of up 975% before breaking. These composite fibers exhibit interesting reversible mechanical and electrical characteristics, which are applied to demonstrate their strain gauging capabilities. This will facilitate their potential applications in strain sensing or elastic electrodes. Here, the fabrication and characterization of highly stretchable electrically conducting SIBS-P3HT fibers using a solvent/non-solvent wet-spinning technique is reported. This fabrication method combines the processability of conducting SIBS-P3HT blends with wet-spinning, resulting in fibers that could be easily spun up to several meters long. The resulting composite fiber materials exhibit an increased stiffness (higher Young’s modulus) but lower ductility compared to SIBS fibers. The fibers’ reversible mechanical and electrical characteristics are applied to demonstrate their strain gauging capabilities.

Dust as an unalterable deteriorative factor affecting PV panel's efficiency: why and how

Electricity generation from solar energy has a great potential since it relies mainly on an abundant and clean source. However, there are many alterable and unalterable factors that can govern a PV module's efficiency. Dust is one of the location-dependent environmental factors that falls under the unalterable factors group. It can degrade the efficiency of a PV panel by causing physical damages, by attenuating the incoming solar radiation and by causing temperature rise, which results in changes in panel's electrical characteristics. Degree of degradation depends mainly on the deposition density, which is governed by various factors. Dust accumulation of 20 g/m2 on a PV panel reduces short circuit current, open circuit voltage and efficiency by 15–21%, 2–6% and 15–35% respectively. This work reviews, elaborates and summarizes the effects of dust on solar panel efficiency and the factors governing dust deposition on PV panel.

Making PBL teams successful : a study on student diversity in a first year electrical engineering programme

Problem based learning (PBL) is a group learning environment that involves a radical change in the way students learn and the role that academic staff play in facilitating learning. The PBL approach claims to build extended technological and social understandings as it offers a context for development of autonomous learners. It has an emphasis on collective and individual learning motivation and decision-making behaviours.

In this paper, we present the responses of students to the heterogeneous characteristic of PBL teams in a first year electrical engineering degree course at an Australian University. The learning cultures in PBL teams that emerge as a result of the diverse characteristics of teams are also presented in this paper.

A number of PBL teams were observed and interviewed throughout their first year course with their consent. Analysis of the data collected about students’ learning and outcomes in PBL teams informed the ways in which individual students approach their learning, the ways in which they control, regulate and direct their learning individually and as a group and the extent to which they participate, engage and thereby learn in the course.

It is evident that some students have a strong influence on the behaviour of other students in their team. These students also influenced what is learnt as a team, the ways in which they interrelated, worked as a team and problem solved in changing circumstances. Therefore, when designing student teams for PBL academics should not assume that a mono-cultural group or a mixed-ability group of students will work successfully together. We think that the results of this research inform both the design of PBL courses and the facilitation of PBL groups to accomplish successful group learning outcomes.

Characteristics and applications of energy storage system to power network - A review

Maintaining reliability and stability of a power systems in transmission and distribution level becomes a big challenge in present scenario. Grid operators are always responsible to maintain equilibrium between available power generation and demand of end users. Maintaining grid balance is a bigger issue, in case of any unexpected generation shortage or grid disturbance or integration of any renewable energy sources like wind and solar power in the energy mix. In order to compensate such imbalance and to facilitate more renewable energy sources with the grid, energy storage system (ESS) started to be playing an important role with the advancement of the state of the art technology. ESS can also help to get reduction in greenhouse gas (GHG) emission by means of integrating more renewable energy sources to the grid. There are various types of Energy Storage (ES) technologies which are being used in power systems network from large scale (above 50MW) to small scale (up to 100KW). Based on the characteristics, each storage technology has their own merits and demerits. This paper carried out extensive review study and verifies merits and demerits of each storage technology and identifies the suitable technology for the future. This paper also has conducted feasibility study with the aid of E-SelectTM tool for various ES technologies in applications point of view at different grid locations. This review study helps to evaluate feasible ES technology for a particular electrical application and also helps to develop smart hybrid storage system for grid applications in efficient way.

Analysis of lightning current characteristics to investigate lightning strike damages to energy pipeline

Australia is one of the most lightning prone area on earth. Lightning strikes have been identified as one of the most common cause of energy pipeline damage in Australia. Therefore, a suitable protection schemes and mitigation strategies against lighting strike damage is very important for Australian pipeline industry. There are a number of research on lighting protection of establishment such as, power systems, buildings, and telecommunications systems, however, very few publications could be found which discuss about protection of pipeline from lightning strike. Assessment of effects in buried pipeline, due to lighting strikes is important. Existing models do not account adequately the effect of the characteristics of soil breakdown channels intercepted by the buried object. This paper aims to investigate the characteristics of lightning current on metal object under the soil of strike point so that lighting attachment to energy pipeline could be understand and a protection technique could be developed. Along with lightning current characteristics, lightning attachment process, distribution method, soil resistivity, propagation of lightning current in soil with a buried pipeline, pipeline electrical properties and other related areas and technologies is explored. The study shows that though there are some research on characteristics of induced on simple buried structures like narrow telephone cable or residential gas pipe, but no substantial research have been done on large comparatively complex structures like buried energy pipelines. Also dynamic behavior of soil and the object to be protected not been considered in protections schemes and experiments.

Thermal and rheological characteristics of biobased carbon fiber precursor derived from low molecular weight organosolv lignin

In the present work, electrospinnability as well as thermal, rheological, and morphological characteristics of low molecular weight hardwood organosolv lignin, as a potential precursor for carbon fiber, was investigated. Submicromter biobased fibers were electrospun from a wide range of polymer solutions with different ratios of organosolv lignin to polyacrylonitrile (PAN). Rheological studies were conducted by measuring viscosity, surface tension, and electrical conductivity of hybrid polymer solutions, and used to correlate electrospinning behavior of solutions with the morphology of the resultant electrospun composite fibers. Using scanning electron microscopy (SEM) images, the solutions that led to the formation of bead-free uniform fibers were found. Differential scanning calorimetry (DSC) analysis revealed that lignin-based fibers enjoy higher decomposition temperatures than that of pure PAN. Thermal stability of the lignin-based fibers was investigated by thermogravimetric analysis (TGA) indicating a high carbon yield of above 50% at 600 °C, which is highly crucial in the production of low-cost carbon fiber. It was also observed that organosolv lignin synergistically affects thermal decomposition of composite fibers. A significant lower activation energy was found for the pyrolysis of lignin-derived electrospun fibers compared to that of pure PAN.

Analyzing systolic-diastolic interval interaction characteristics in diabetic cardiac autonomic neuropathy progression

Cardiac autonomic neuropathy (CAN), one of the major complications in diabetes, if detected at the subclinical stage allows for effective treatment and avoiding further complication including cardiovascular pathology. Surface ECG (Electrocardiogram)-based diagnosis of CAN is useful to overcome the limitation of existing cardiovascular autonomic reflex tests traditionally used for CAN identification in clinical settings. The aim of this paper is to analyze the changes in the mechanical function of the ventricles in terms of systolic-diastolic interval interaction (SDI) from a surface ECG to assess the severity of CAN progression [no CAN, early CAN (ECAN) or subclinical CAN, and definite CAN (DCAN) or clinical CAN]. ECG signals recorded in supine resting condition from 72 diabetic subjects without CAN (CAN-) and 70 diabetic subjects with CAN were analyzed in this paper. The severity of CAN was determined by Ewing's Cardiovascular autonomic reflex tests. Fifty-five subjects of the CAN group had ECAN and 15 subjects had DCAN. In this paper, we propose an improved version of the SDI parameter (i.e., TQ/RR interval ratio) measured from the electrical diastolic interval (i.e., TQ interval) and the heart rate interval (i.e., RR interval). The performance of the proposed SDI measure was compared with the performance of the existing SDI measure (i.e., QT/TQ interval ratio). The proposed SDI parameter showed significant differences among three groups (no CAN, ECAN, and DCAN). In addition, the proposed SDI parameter was found to be more sensitive in detecting CAN progression than other ECG interval-based features traditionally used for CAN diagnosis. The modified SDI parameter might be used as an alternative measure for the Ewing autonomic reflex tests to identify CAN progression for those subjects who are unable to perform the traditional tests. These findings could also complement the echocardiographic findings of the left ventricular diastolic dysfunction by providing additional information about alteration in systolic and diastolic intervals in heart failure.

Robust time-spread echo watermarking using characteristics of host signals

A robust audio watermarking method based on the time-spread (TS) echo hiding scheme is proposed. Compared with existing TS watermarking methods, the approach is more robust as it exploits the characteristics of host signals in the encoding stage. Theoretical analysis and simulation examples demonstrate the effectiveness and advantages of the method.