620 research outputs found
Sistem Penilaian Kinerja Pegawai dengan Metode Analytical Hierarchy Process (Ahp) (Studi Kasus pada Kantor Stasiun Meteorologi El Tari Kupang)
Penilaian prestasi kinerja adalah suatu proses penilaian yang dilakukan pemimpin Perusahaan secara sistematik berdasarkan pekerjaan yang ditugaskan kepada pegawainya. Stasiun Meteorologi El Tari Kupang merupakan salah satu instansi pemerintahan yang menerapkan penilaian kinerja pegawai untuk tujuan promosi jabatan ataupun pemilihan pegawai berprestasi. Untuk membantu Kepala Stasiun Meteorologi El Tari Kupang dalam proses penilaian kinerja pegawai maka sangat penting dibangun sebuah sistem penilaian kinerja. Penerapan Sistem Pendukung Keputusan (SPK) terkomputerisasi yang mampu membantu proses penilaian kinerja pegawai. Penelitian ini menggunakan metode Analytical Hierarchy Process (AHP) untuk penilaian prestasi kerja pegawai. Sistem yang dibangun berbasis web dan menggunakan kriteria penilaian pegawai meliputi kedisiplinan, prestasi kerja, tanggung jawab dan kompetensi bidang. Hasil analisis yang didapat mampu memberikan urutan rangking terbaik, sehingga menghasilkan kriteria dengan bobot tertinggi yang dapat digunakan sebagai pertimbangan dalam pengambilan keputusan. Hasil pengujian menunjukkan bahwa aplikasi sistem penilaian kinerja pegawai Stasiun Meteorologi El Tari Kupang dengan metode Analytical Hierarchy Proccess dapat berfungsi dengan baik. Hasil perbandingan nilai akhir antara perhitungan sistem dengan perhitungan metode AHP secara manual memiliki nilai yang sama. Hasil perbandingan perangkingan antara sistem dengan data penilaian manual Kantor Stasiun Meteorologi El Tari Kupang mempunyai persamaan urutan perangkingan sebanyak 9 dari 16 pegawai
Achievement of prolonged oxygen detection in room-temperature ionic liquids on mechanically polished platinum screen-printed electrodes
The demonstration of prolonged amperometric detection of oxygen in room-temperature ionic liquids (RTILs) was achieved by the use of mechanical polishing to activate platinum screen-printed electrodes (Pt-SPEs). The RTILs studied were 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) and N-butyl-N-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4mpyrr][NTf2]). It was found that voltammetry on polished Pt-SPEs exhibited less deterioration (in terms of voltammogram shapes, stability of peak currents, and appearance of contaminant peaks) from long-term consecutive cycling under 100% vol oxygen flow in both RTILs. The detection capability of these RTIL/Pt-SPE systems, initially subjected to long-term consecutive voltammetric cycling, was also investigated by cyclic voltammetry (CV) and long-term chronoamperometry (LTCA). Current versus concentration plots were linear on both unpolished and polished electrodes for 10-100% vol O2 (using CV) and 0.1-5% vol O2 (using LTCA). However, sensitivities and limits of detection (LODs) from CV were found to improve significantly on polished electrodes compared to unpolished electrodes, particularly in [C2mim][NTf2], but also moderately in [C4mpyrr][NTf2]. The lowest LODs (of ca. 0.1% vol O2) were found on polished SPEs using LTCA, with the most stable responses observed in [C4mpyrr][NTf2]. Calibration graphs could not be obtained on unpolished electrodes in both RTILs using LTCA. The results show that polishing markedly improves the analytical performances of Pt-SPEs for oxygen sensing in RTILs. The reusability of such disposable Pt-SPEs, after the surfaces had been experimentally fouled, was also demonstrated through the use of polishing. Mechanical polishing of Pt-SPE devices offers a viable approach to performance improvement for amperometric gas sensing. © 2016 American Chemical Society
Towards an optimized design method for pv-powered consumer and professional applications - the syn-energy project
Electrochemical Behavior of Chlorine on Platinum Microdisk and Screen-Printed Electrodes in a Room Temperature Ionic Liquid
As a result of the toxic and corrosive nature of chlorine gas, simple methods for its detection are required for monitoring and control purposes. In this paper, the electrochemical behavior of chlorine on platinum working electrodes in the room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C2mim][NTf2]) is reported, as a basis for simple sensor devices. Cyclic voltammetry (CV) and chronoamperometry (CA) on a Pt microelectrode revealed the two-electron reduction of Cl2 to chloride ions. On the CV reverse sweep, an oxidation peak due to the oxidation of chloride was observed. The reduction process was diffusion controlled at the concentrations studied (≤4.5% in the gas phase), in contrast to a previous report (J. Phys. Chem. C2008, 112, 19477), which examined only 100% chlorine. The diffusion-controlled currents were linear with gas-phase concentration. Fitting of the CA transients to the Shoup and Szabo expression gave a diffusion coefficient for chlorine in the RTIL of ca. 2.6 × 10–10 m2 s–1. Furthermore, determination of the equilibrium concentration of Cl2 in the RTIL phase as a function of gas-phase concentration enabled a value of 35 to be determined for the Henry’s law dimensionless volatility constant. The electrochemical behavior of chlorine on a Pt screen-printed electrode was also investigated, suggesting that these devices may be useful for chlorine detection in conjunction with suitable RTILs
Refined saddle-point preconditioners for discretized Stokes problems
This paper is concerned with the implementation of efficient solution algorithms for elliptic problems with constraints. We establish theory which shows that including a simple scaling within well-established block diagonal preconditioners for Stokes problems can result in significantly faster convergence when applying the preconditioned MINRES method. The codes used in the numerical studies are available online
Colloquium: The transport properties of graphene: An introduction
An introduction to the transport properties of graphene combining
experimental results and theoretical analysis is presented. In the theoretical
description simple intuitive models are used to illustrate important points on
the transport properties of graphene. The concept of chirality, stemming from
the massless Dirac nature of the low energy physics of the material, is shown
to be instrumental in understanding its transport properties: the conductivity
minimum, the electronic mobility, the effect of strain, the weak
(anti-)localization, and the optical conductivity.Comment: As publishe
Void-Assisted Ion-Paired Proton Transfer at Water-Ionic Liquid Interfaces.
At the water-trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate ([P14,6,6,6 ][FAP]) ionic liquid interface, the unusual electrochemical transfer behavior of protons (H(+) ) and deuterium ions (D(+) ) was identified. Alkali metal cations (such as Li(+) , Na(+) , K(+) ) did not undergo this transfer. H(+) /D(+) transfers were assisted by the hydrophobic counter anion of the ionic liquid, [FAP](-) , resulting in the formation of a mixed capacitive layer from the filling of the latent voids within the anisotropic ionic liquid structure. This phenomenon could impact areas such as proton-coupled electron transfers, fuel cells, and hydrogen storage where ionic liquids are used as aprotic solvents
Complex phylogeographic history of central African forest elephants and its implications for taxonomy
Background: Previous phylogenetic analyses of African elephants have included limited numbers of forest elephant samples. A large-scale assessment of mitochondrial DNA diversity in forest elephant populations here reveals a more complex evolutionary history in African elephants as a whole than two-taxon models assume. Results: We analysed hypervariable region 1 of the mitochondrial control region for 71 new central African forest elephants and the mitochondrial cytochrome b gene from 28 new samples and compare these sequences to other African elephant data. We find that central African forest elephant populations fall into at least two lineages and that west African elephants (both forest and savannah) share their mitochondrial history almost exclusively with central African forest elephants. We also find that central African forest populations show lower genetic diversity than those in savannahs, and infer a recent population expansion. Conclusion: Our data do not support the separation of African elephants into two evolutionary lineages. The demographic history of African elephants seems more complex, with a combination of multiple refugial mitochondrial lineages and recurrent hybridization among them rendering a simple forest/savannah elephant split inapplicable to modern African elephant populations
Electrochemical Oxidation and Sensing of Methylamine Gas in Room Temperature Ionic Liquids
The electrochemical behaviour of methylamine gas in several room temperature ionic liquids (RTILs), [C2mim][NTf2], [C4mim][NTf2], [C6mim][FAP], [C4mpyrr][NTf2], [C4mim][BF4], and [C4mim][PF6] has been investigated on a Pt microelectrode using cyclic voltammetry. A broad oxidation wave at approximately 3 V, two reduction peaks and another oxidation peak was observed. A complicated mechanism is predicted based on the voltammetry obtained, with ammonia gas as a likely by-product. The currents obtained suggest that methylamine has a high solubility in RTILs, which is important for gas sensing applications. The analytical utility of methylamine was then studied in [C4mpyrr][NTf2] and [C2mim][NTf2]. A linear calibration graph with an R2 value of 0.99 and limits of detection of 33 and 34 ppm were obtained respectively, suggesting that RTILs are favourable non-volatile solvents for the electrochemical detection of highly toxic methylamine gas
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