The Performance Evaluation of SMA Spring as Actuator for Gripping Manipulation

This paper is to present the evaluation of a TiNi Shape Memory Alloy (SMA) spring as actuator for the gripping manipulation. The SMA spring employed was a TiNi tensile spring which has a diameter of 50 mm wire and 350 gram hanging mass. The gripper fabricated consists of two fingers and each finger is actuated by the SMA spring. The total angular displacement of the gripper is 300. The power consumptions, the movements and force generations experimentations have been conducted. The DC signal and PWM signal with 12, 12Hz, 25Hz, 125Hz, 250Hz and the 1150Hz have been employed for driving the SMA. The experimental results indicated that the 125Hz of PWM signal was likely to be had a better performance than the other signals. The 125Hz PWM signal generated faster movement, lower power consumption, and constant rate of force. In this study, closed-loop control for gripping manipulation was also conducted. The close loop controller used is PID controller. The Ziegler-Nichols method has been used to predict the optimal gain of the controller, but the best performance was determined by experimentally tuning of the gains. The experimental results indicated that the PID controller is likely to be reliable controller for gripping manipulation of the SMA spring. To obtain the better performance, it is important to consider the SMA cooling responses and the long time of retain in certain position of the gripper

Optimization of operating parameters of novel composite adsorbent for organic pollutants removal from POME using response surface methodology

The present work aimed to develop a novel composite material made up of activated cow bone powder (CBP) as a starting material for reducing chemical oxygen demand (COD) and ammonia-nitrogen (NH3eN) from palm oil mill effluent (POME). The optimization of the reduction efficiency was investigated using response surface methodology (RSM). Six independent variables used in the optimization experiments include pH (4e10), speed (0.27e9.66 rcf), contact time (2e24 h), particle size (1e4.35 mm), dilution factor (100e500) and adsorbent dosage (65e125 g/L). The chemical functional groups were determined using Fourier transform irradiation (FTIR). The elemental composition were detected using SEM-EDX, while thermal decomposition was investigated using thermo gravimetric analysis (TGA) in order to determine the effects of carbonization temperature on the adsorbent. The results revealed that the optimal reduction of COD and NH3eN from raw POME was observed at pH 10, 50 rpm, within 2 h and 3 mm of particle size as well as at dilution factor of 500 and 125 g L�1 of adsorbent dosage, the observed and predicted reduction were 89.60 vs. 85.01 and 75.61 vs. 74.04%, respectively for COD and NH3eN. The main functional groups in the adsorbent were OH, NeH, C]O, C]C, CeOeC, CeOeH, and CH. The SEMEDX analysis revealed that the CBP-composite has a smooth surface with high contents of carbon. The activated CBP has very stable temperature profile with no significant weight loss (9.85%). In conclusion, the CBP-composite investigated here has characteristics high potential for the remediation of COD and NH3eN from raw POME

Single measurement detection of individual cell ionic oscillations using an n-type semiconductor - Electrolyte interface

Pollen tubes are used as models in studies on the type of tip-growth in plants. They are an example of polarised and rapid growth because pollen tubes are able to quickly invade the flower pistil in order to accomplish fertilisation. How different ionic fluxes are perceived, processed or generated in the pollen tube is still not satisfactorily understood. In order to measure the H+, K+, Ca2+ and Cl- fluxes of a single pollen tube, we developed an Electrical Lab on a Photovoltaic-Chip (ELoPvC) on which the evolving cell was immersed in an electrolyte of a germination medium. Pollen from Hyacinthus orientalis L. was investigated ex vivo. We observed that the growing cell changed the (redox) potential in the medium in a periodic manner. This subtle measurement was feasible due to the effects that were taking place at the semiconductor-liquid interface. The experiment confirmed the existence of the ionic oscillations that accompany the periodic extension of pollen tubes, thereby providing - in a single run - the complete discrete frequency spectrum and phase relationships of the ion gradients and fluxes, while all of the metabolic and enzymatic functions of the cell life cycle were preserved. Furthermore, the global 1/f α characteristic of the power spectral density, which corresponds to the membrane channel noise, was found

Influence of Solar Heating on the Performance of Integrated Solar Cell Microstrip Patch Antennas

The integration of microstrip patch antennas with photovoltaics has been proposed for applications in autonomous wireless communication systems located on building façades. Full integration was achieved using polycrystalline silicon solar cells as both antenna ground plane and direct current power generation in the same device. An overview of the proposed photovoltaic antenna designs is provided and the variation characterised of the electromagnetic properties of the device with temperature and solar radiation. Measurements for both copper and solar antennas are reported on three different commercial laminates with contrasting values for thermal coefficient of the dielectric constant

Együtt-párologtatott négykomponensű félvezető vékonyréteg fotovoltaikus célra = Co-evaporated four-component semiconductor thin films for photovoltaics

A CIGS PV szerkezet kutatásának célja az együtt-párologtatásos előállításnál fellépő folyamatok megismerése; és az n-típusú puffer-réteg létrehozása vákuumtechnikailag zárt ciklusba rendezhető módon. Utóbbit az atomi réteg-leválasztási technika hazai bevezetésével oldottuk meg. Kb. 200 ciklusban Zn-és 2 at% Al prekurzor-technikával Al-mal adalékolt ZnO-rétegek üveg hordozón T= 210-220°C-on reprodukálhatóan kialakíthatók n=1,2•1021cm-3 adalékkoncentrációval, µ= 0.7 cm2/Vs mozgékonysággal ill. ρ≈2 mΩcm (1 ill. 7 mΩcm laterális és normális) vezetőképességgel. A CIGS rétegnövesztést ún. flash-párologtatásos módszerrel és utólagos szelenizációval vizsgáltuk. Ampullában, együttes párologtatással (T=500°C, t=15min) csak kalkopirit összetevők mutathatók ki, a hőkezelés csak a Ga-tartalmat befolyásolja. Az ideális CuIn0,8Ga0,2Se2 összetétel 10-15 perces hőkezeléssel beállítható a szokásos morfológiával, amit konformálisan fed be a kb. 40nm ALD pufferréteg . Üvegen, Mo-elektródra párologtatott (In, Ga) és porlasztott (Cu) fémösszetevők rétegsorrendjének szerepe döntő utólagosan szelenizált rétegszerkezeten. Felpárologtatott Se-forrás hőkezelésével (változó gőznyomáson) vákuumban a szelenizáció nem sikeres, de konstans gőznyomáson (ampullában) tökéletes, ha a fémrétegek sorrendje In, Ga, Cu. | The research on CuInGaSe2 (CIGS) thin film PV structures aimed at understanding of fundamental phenomena at the co-evaporation of the absorber layer; and the development of n-type buffer-layer by an integrable vacuum-method. Latter problem was solved by the adoption of the Atomic Layer Deposition (ALD) technique. In ca. 200 cycles of alternating Zn and ca. 2at% Al precursor pulses Al-doped ZnO layers on glass substrates could be formed reliably at T= 210-220°C with n=1,2•1021cm-3 doping concentration, µ= 0.7 cm2/Vs mobility and ρ≈2 mΩcm (1 vs. 7 mΩcm lateral and normal) resistivity. CIGS layer growth by the "flash-evaporation" method and with the post-selenisation of the metallic precursors was studied. Co-evaporation at T=500°C, t=15min results in solely chalcopyrite components, annealing time affects only the Ga-content in the layer. The composition CuIn0,8Ga0,2Se2 ideal for PV application can be set by an annealing for 10-15 min with the usual morphology, to be covered conformally by the ca. 40nm ALD buffer. The influence of the sequence of evaporated (In, Ga) and sputtered (Cu) metallic components on Mo-coated glass was studied by structural analyses on post-selenized d= 800…1200 nm layers. By the annealing of evaporated Se-source on top in vacuum (i.e. at varying Se vapour pressure) selenization was not successful. At constant vapour pressure (ampoule method) with a metal-layer order of In, Ga, Cu selenization is perfect

Päikeseelementide hübriidnanomaterjalide UV ja nähtava valguse neeldumise analüüs - hafnium dioktsiid ja süsiniknanotorud

Bachelor thesis Energy Application EngineeringSelle bakalaureusetöö eesmärk oli läbi viia spektroskoopiline analüüs nanohübriidmaterjalile koosnevast Hafnium dioktsiidist (HfO2) ja süsiniknanotorudest (CNT). Uuriti neeldumise lainepikkusi ultraviolett (UV) ja nähtava valguse ergastuse puhul. Eelnevates uuringutes on tuvastatud, et nanohübriid koosnevast CNT’st ja kuupstruktuuriga HfO2 nanoosakestest tekitab fotovoolu tugeva valgustuse puhul UV ja nähtava valguse puhul. Selles töös uuritakse nanohübriidi koosnevast monokliinilisest HfO2-st ja CNT-st. Lõputöö üheks ülesandeks oli uurida kuidas mõjub HfO2/CNT vahekorra muutmine materjali optilistele omadustele. Eesmärgi saavutamiseks segati kokku kolm nanohübriidsegu, mis sisaldasid 5 mg HfO2-d ja 1, 2, 5% CNT-d kogukaalust, ning mõõdeti segude valgusneelduvust erinevate lainepikkuste puhul kasutades spektrofotomeetrit. Analüüsi tulemusena selgus, et HfO2-CNT nanohübriid on paremate optiliste omadustega võrreldes puhta HfO2 või CNT-ga. HfO2 nanoosakeste puhul märgati neelduvuse tipplainepikkuseid 230 nm ja 265 nm juures. Tipp 230nm juures on seotud elektronide liikumisega HfO2 aatomite valentstsoonist juhtivustsooni, ületades nende vahe. Tipp 265 nm juures iseloomustab molekulaarseid struktuurisi defekte ja elektronide liikumist pindmistele alamelektronkihtidele. Segades kokku HfO2 ja CNT täheldati uue neeldumistipu ilmumist lainepikkusel 276 nm juures, mis vastab pindmisele vastasmõjule HfO2 defektseisundite ja CNT π-plasmoni vahel. Tõstes CNT sisaldust, muutusid pindmised defektseisundid passiivseteks ning neelduvus 276 nm juures langes. Parima neeldumisega osutus nanohübriid, mis sisaldas 1% CNT-d segu kogukaalust.The objective of this thesis was to perform an absorption spectroscopy analysis on a nanohybrid composite of Hafnium dioxide (HfO2) and carbon nanotube (CNT). The absorption wavelengths were studied under excitations ranging from the Ultraviolet (UV) to the visible spectrum. In a previous research, it was demonstrated that the HfO2-CNT nanohybrid containing cubic HfO2 produces a photocurrent when illuminated with UV and visible light (200-700nm). The current study’s key aim was to study the HfO2-CNT nanohybrid containing monoclinic HfO2. One of the goals was to study the absorption behavior when the concentration of CNT was varied in the nanocomposite. Three samples containing 1, 2, and 5 wt.% of CNT were prepared and studied using a spectrophotometer. The spectroscopic study revealed that the new nanohybrid has enhanced optical properties as compared to pure HfO2. For the HfO2 nanoparticles alone absorption at 230 nm and 265 nm was observed, 230nm corresponding to the fundamental gap of HfO2 and 265 nm corresponding to defect states of HfO2. However, when CNT was added, a new absorption peak at 276 nm was observed, corresponding to the surface interactions between HfO2 defect states and π-plasmon of CNT. The results suggest that when CNT is added, the defect states become passivated and absorption at 276 nm drops

Testing the Efficacy of the Synthesis of Iron Antimony Sulfide Powders from Single Source Precursors

From MDPI via Jisc Publications RouterHistory: accepted 2021-07-21, pub-electronic 2021-08-02Publication status: PublishedFunder: D.J.L. and F.A. thank the EPSRC for funding (EP/R020590/1); Grant(s): (EP/R020590/1)The antimony-iron sulfide system in general does not produce alloys below 540 °C from traditional solid-state methods. However, single source precursors have been known to produce unexpected products that arise from kinetically trapped polymorphs. In this paper, we test the efficacy of this approach toward the Fe-Sb-S system. Antimony and iron diethyldithiocarbamate complexes of the form Sb[S2CN(Et2)]3 (1) and Fe[S2CN(Et2)]3 (2) were synthesised, characterised, and used as single-source precursors for the preparation of Sb2S3, FexSy, and mixed iron antimony sulfide Sb2(1−x)Fe2xS3 (0 ≥ x ≥ 1) powders using the solvent-less thermolysis method at different temperatures ranging from 300 to 475 °C. The effect of different mole fractions of the iron precursor was evaluated on morphology, shape, and optical and magnetic properties of Sb2(1−x)Fe2xS3 (0 ≥ x ≥ 1). The obtained powders were characterized by X-ray diffraction (XRD), Raman spectroscopy scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, magnetometer measurement, and UV/vis/NIR spectroscopy. The results demonstrated that the crystalline structure, morphology, and elemental composition of the samples changed with the mole fraction of the precursor. There was significant phase separation between Sb and Fe sulfides noted from EDX spectroscopic mapping, yet an optoelectronic study monitoring the direct band gap energy of antimony sulfide shows that the band gap energy increases as a function of Fe content, which suggests limited alloying is possible from the single source route

OpenFOAM implementation for the study of streamwise vortex-induced vibration-based energy harvester for sensor networks

The study of streamwise vortex induced vibration has reached a level of maturity that allows it to be harnessed to generate power. However, studies have primarily concentrated on the variables that measured through point-based instruments. This severely limits our understanding of the fluid forcing mechanism that results in the vibration of the elastically supported bluff body. We proposed the usage of computational fluid dynamics: the open source C++ libraries of OpenFOAM. To implement this successfully to the streamwise vortex-induced vibration problem, which involves near-wall fluid-structure interaction, we explored the method of dynamic mesh handling in OpenFOAM for six degrees of freedom motion of a rigid body fully submerged in fluid. Finally, we argued for the usage of arbitrarily coupled mesh interface to overcome the problem of severely distorted mesh in tight gaps between two walls. We run a short simulation to test this setup and found that the case runs uninterrupted, unlike its former counterpart that relies solely on cell displacement diffusion, suggesting the potential success of a further converged solution of the setup when running on a more powerful machine

Hierarchical macro-nanoporous metals for leakage-free high-thermal conductivity shape-stabilized phase change materials

Impregnation of Phase Change Materials (PCMs) into a porous medium is a promising way to stabilize their shape and improve thermal conductivity which are essential for thermal energy storage and thermal management of small-size applications, such as electronic devices or batteries. However, in these composites a general understanding of how leakage is related to the characteristics of the porous material is still lacking. As a result, the energy density and the antileakage capability are often antagonistically coupled. In this work we overcome the current limitations, showing that a high energy density can be reached together with superior anti-leakage performance by using hierarchical macro-nanoporous metals for PCMs impregnation. By analyzing capillary phenomena and synthesizing a new type of material, it was demonstrated that a hierarchical trimodal macro-nanoporous metal (copper) provides superior antileakage capability (due to strong capillary forces of nanopores), high energy density (90vol% of PCM load due to macropores) and improves the charging/discharging kinetics, due to a three-fold enhancement of thermal conductivity. It was further demonstrated by CFD simulations that such a composite can be used for thermal management of a battery pack and unlike pure PCM it is capable of maintaining the maximum temperature below the safety limit. The present results pave the way for the application of hierarchical macro-nanoporous metals for high-energy density, leakage-free, and shape-stabilized PCMs with enhanced thermal conductivity. These innovative composites can significantly facilitate the thermal management of compact systems such as electronic devices or high-power batteries by improving their efficiency, durability and sustainabilit