Multi-use two wheel tractor operated fertilizer applicator for Coconut cultivation

Unfortunately, it is observed that application of comical fertilizers is low in the coconut sector partlydue to high wages and scarcity of labour.The purpose of mechanization in coconut cultivation is to produce more from existing land. Machineryis a complimentary input required to achieve higher land productivity. Additional benefits to the usermay be associated with a reduction in drudgery of farm work greater leisure, or reduction of risk.Use of manpower for the application of fertilizer is uneconomical due to high labor cost. Thereforepower tiller operated fertilizer applicator for coconut cultivation was designed and constructed. Thismachine is not only useful to broadcast fertilizer on the soil but also to mix it with the soil close to thepalm on the weeded surface.The designed machine consists offertilizer distribution unit and rotary unit. The Maximum spreadingwidth in meter, Machine discharge rate in gr/min and Uniformity coefficient of spray distribution,were considered as criteria for comparison of merits and demerits. The results showed that theMaximum spreading width and Machine discharges rate were 0.7m, and 150 - 230 gr/min, respectively.The cost of production of the designed power tiller operated fertilizer applicator was RS.l 0,000.00

Design and development of power tiller operated multipurpose whole stick harvester especially for sugarcane

In Sri Lanka cane harvesting is done manually using various types of hand knives. This method ofharvesting not only consumes much time but also requires much skilled labourers. But nowadayslabourers are becoming scarce and costly, particularly in sugarcane cultivation areas. This is due todiversion oflabour to other more remunerative work in industry, construction, business and diversionof labour to other crops.It is difficult to employ heavy machines in Sri Lanka due to various reasons such as, fragmented andsmall holdings with small and irregular fields, diverse cropping patterns followed, the cultivation practices which have been developed for manual harvest and poor farmers who cannot afford costly machines.Therefore Power tiller operated whole stick harvester prototype was designed and constructed. Thedesigned machine consists of reversible cutting device, power transmission unit with clutch mechanismand Cane shifting device. The Maximum cutting width, Machine capacity and Traveling speed wereconsidered as criteria for comparison of merits and demerits with existing manual method. The resultsshowed that maximum cutting width, Machine capacity and Traveling speed were 1.2m, 0.8 ha/dayand 0.75 km/hr respectively. The cost of production of the designed Sugarcane harvester wasRs.20,OOO.0

Room temperature photocurrent spectroscopy of single zincblende and wurtzite InP nanowires

Simple photolithographic techniques are used to fabricate single InPnanowire devices with back-to-back Schottky barriers. Direct imaging of the photoresponse shows that the active regions of the device are spatially localized near the reverse-biased Schottky barrier. By tuning the laser excitation energy from below to well above the energy gap,photocurrentspectroscopy can illuminate the zincblende or wurtzite nature of the nanowire device even at room temperature.We acknowledge the support of the NSF through DMR Grant Nos. 0806700 and 0804199, and ECCS Grant No. 0701703, as well as the University of Cincinnati Institute for Nanoscale Science and Technology. The Australian authors acknowledge support from the Australian Research Council

Correlating the nanostructure and electronic properties of InAs nanowires

The electronic properties and nanostructure of InAs nanowires are correlated by creating multiple field effect transistors (FETs) on nanowires grown to have low and high defect density segments. 4.2 K carrier mobilities are ~4X larger in the nominally defect-free segments of the wire. We also find that dark field optical intensity is correlated with the mobility, suggesting a simple route for selecting wires with a low defect density. At low temperatures, FETs fabricated on high defect density segments of InAs nanowires showed transport properties consistent with single electron charging, even on devices with low resistance ohmic contacts. The charging energies obtained suggest quantum dot formation at defects in the wires. These results reinforce the importance of controlling the defect density in order to produce high quality electrical and optical devices using InAs nanowires.Comment: Related papers at http://pettagroup.princeton.ed

Effect of the GaAsP shell on optical properties of self-catalyzed GaAs nanowires grown on silicon

We realize growth of self-catalyzed core-shell GaAs/GaAsP nanowires (NWs) on Si substrates using molecular-beam epitaxy. Transmission electron microscopy (TEM) of single GaAs/GaAsP NWs confirms their high crystal quality and shows domination of the zinc-blende phase. This is further confirmed in optics of single NWs, studied using cw and time-resolved photoluminescence (PL). A detailed comparison with uncapped GaAs NWs emphasizes the effect of the GaAsP capping in suppressing the non-radiative surface states: significant PL enhancement in the core-shell structures exceeding 2000 times at 10K is observed; in uncapped NWs PL is quenched at 60K whereas single core-shell GaAs/GaAsP NWs exhibit bright emission even at room temperature. From analysis of the PL temperature dependence in both types of NW we are able to determine the main carrier escape mechanisms leading to the PL quench

Probing the valence band structure of wurtzite InP nanowires by photoluminescence excitation spectroscopy

We use time-resolved photoluminescence and photoluminescence excitation spectroscopy to obtain the valence band parameters of wurtzite InP nanowires. We observe the A, B, and C hole bands for these nanowires and obtain both the crystal field and the spin-orbit energies for wurtzite InP nanowires

Carrier thermalization dynamics in single zincblende and wurtzite InP nanowires

Using transient Rayleigh scattering (TRS) measurements, we obtain photoexcited carrier thermalization dynamics for both zincblende (ZB) and wurtzite (WZ) InP single nanowires (NW) with picosecond resolution. A phenomenological fitting model based on direct band-to-band transition theory is developed to extract the electron-hole–plasma density and temperature as a function of time from TRS measurements of single nanowires, which have complex valence band structures. We find that the thermalization dynamics of hot carriers depends strongly on material (GaAs NW vs InP NW) and less strongly on crystal structure (ZB vs WZ). The thermalization dynamics of ZB and WZ InP NWs are similar. But a comparison of the thermalization dynamics in ZB and WZ InP NWs with ZB GaAs NWs reveals more than an order of magnitude slower relaxation for the InP NWs. We interpret these results as reflecting their distinctive phonon band structures that lead to different hot phonon effects. Knowledge of hot carrier thermalization dynamics is an essential component for effective incorporation of nanowire materials into electronic devices

Quantum confinement of excitons in wurtzite InP nanowires

Exciton resonances are observed in photocurrent spectra of 80 nm wurtzite InP nanowire devices at low temperatures, which correspond to transitions between the A, B, and C valence bands and the lower conduction band. Photocurrent spectra for 30 nm WZ nanowires exhibit shifts of the exciton resonances to higher energy, which are consistent with finite element calculations of wavefunctions of the confined electrons and holes for the various bands