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Pembuatan Komposit Bata Merahdari Limbah Padat Pabrik Minyak Nabati
Pengembangan teknologi proses bata merah limbah padat pabrik minyak nabati, yaitu spent bleaching earth telah dilakukan. Tujuan penelitian adalah untuk mengkaji pemanfaatan limbah pabrik minyak nabati sebagai bahan baku pembuatan bata merah yang sekiranya dapat berperan untuk mengatasi masalah lingkungan dari limbah padat yang menumpuk di lokasi pabrik minyak nabati. Penelitian dilaksanakan dalam dua tahap yakni, penelitian pendahuluan untuk mendapatkan komposisi bahan yang baik dan penelitian lanjutan yaitu pembuatan bata merah skala teknis produksi. Hasil penelitian pendahuluan menunjukkan bahwa bata percobaan untuk perlakuan bahan A1-F1 memiliki karakteristik sedikit plastis s/d agak plastis, tidak retak dan tidak bengkok saat dikeringkan, dengan susut kering antara 7,5-7,79%, selanjutnya tidak retak dan tidak bengkok setelah dibakar pada suhu Ā±700 oC dengan susut bakar antara 1,92-2,94%. Berdasarkan hasil penelitian pendahuluan tersebut selanjutnya dilakukan pencetakan bata merah skala teknis produksi dengan perlakuan (komposisi campuran bahan) (B): 60 bagian SBE+25 bagian Tanah Liat (TL)+15 bagian Domato; (C): 50 bagian SBE+25 bagian TL+25 bagian Domato; dan (D): 70 bagian SBE+20 bagian TL+10 bagian Domato. Hasil uji fisik kuat tekan bata merah dari limbah padat pabrik minyak nabati menunjukkan bahwa semua perlakuan memenuhi persyaratan. Produk dengan kuat tekan kelas terendah terdapat pada perlakuan (B), yakni 63,30 kg/cmĀ² dan yang tertinggi pada perlakuan (C), yakni 103,30 kg/cmĀ². Bila ditinjau dari semua parameter uji maka produk bata merah perlakuan D memenuhi syarat SNI 152094-2000 dengan kuat tekan pada kelas 100 kg/cmĀ²
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The Use of Layered Freeform Fabrication Technologies to Produce Tissue Engineering Scaffolds for Skull Patches
Congenital skull defects in infants are difficult to correct using metal plates due to the growth of
the skull. Tissue engineering of bone patches could be the answer to help such patients. Custom
scaffolds have been designed based on Computed Tomography (CT) images of the patientās
skull. An in-house developed single screw extruder, casting and a commercial laser cutter has
been evaluated in the fabrication of pure polycaprolactone (PCL) scaffolds as well as PCL mixed
with hydroxyapatite (HA) scaffolds. Evaluation criteria for each process included the ability to
maintain an optimal pore size for cells to proliferate, inclusion of micro surface properties for
cell adhesion, incorporation of hydroxyapatite, and ability to maintain desired shape. The
mechanical properties of the fabricated scaffolds will be presented in this paper as well as initial
cell seeding results with human adipose-derived adult stem (hADAS) cells.Mechanical Engineerin
Far-infrared induced current in a ballistic channel -- potential barrier structure
We consider electron transport in a ballistic multi-mode channel structure in
the presence of a transversely polarized far-infrared (FIR) field. The channel
structure consists of a long resonance region connected to an adiabatic
widening with a potential barrier at the end. At frequencies that match the
mode energy separation in the resonance region we find distinct peaks in the
photocurrent, caused by Rabi oscillations in the mode population. For an
experimental situation in which the width of the channel is tunable via gates,
we propose a method for reconstructing the spectrum of propagating modes,
without having to use a tunable FIR source. With this method the change in the
spectrum as the gate voltage is varied can be monitored.Comment: Submitted to Phys. Rev.
Effect of partially-screened nuclei on fast-electron dynamics
We analyze the dynamics of fast electrons in plasmas containing partially
ionized impurity atoms, where the screening effect of bound electrons must be
included. We derive analytical expressions for the deflection and slowing-down
frequencies, and show that they are increased significantly compared to the
results obtained with complete screening, already at sub-relativistic electron
energies. Furthermore, we show that the modifications to the deflection and
slowing down frequencies are of equal importance in describing the runaway
current evolution. Our results greatly affect fast-electron dynamics and have
important implications, e.g. for the efficacy of mitigation strategies for
runaway electrons in tokamak devices, and energy loss during relativistic
breakdown in atmospheric discharges.Comment: 6 pages, 3 figures, fixed minor typo
Current driven magnetization dynamics in helical spin density waves
A mechanism is proposed for manipulating the magnetic state of a helical spin
density wave using a current. In this paper, we show that a current through a
bulk system with a helical spin density wave induces a spin transfer torque,
giving rise to a rotation of the order parameter.The use of spin transfer
torque to manipulate the magnetization in bulk systems does not suffer from the
obstacles seen for magnetization reversal using interface spin transfer torque
in multilayered systems. We demonstrate the effect by a quantitative
calculation of the current induced magnetization dynamics of Erbium. Finally we
propose a setup for experimental verification.Comment: In the previous version of this paper was a small numerical mistake
made when evaluating equation 3 and 9. The number of digits given in the
calculation of the torque current tensor is reduced to better represent the
accuracy of the calculation. A slightly modified paper have been published in
Phys. Rev. Lett. 96, 256601 (2006) 4 pages 3 figure
Comparison of near-interface traps in AlO/4H-SiC and AlO/SiO/4H-SiC structures
Aluminum oxide (Al2O3) has been grown by atomic layer deposition on n-type
4H-SiC with and without a thin silicon dioxide (SiO2) intermediate layer. By
means of Capacitance Voltage and Thermal Dielectric Relaxation Current
measurements, the interface properties have been investigated. Whereas for the
samples with an interfacial SiO2 layer the highest near-interface trap density
is found at 0.3 eV below the conduction band edge, Ec, the samples with only
the Al2O3 dielectric exhibit a nearly trap free region close to Ec. For the
Al2O3/SiC interface, the highest trap density appears between 0.4 to 0.6 eV
below Ec. The results indicate the possibility for SiC-based MOSFETs with Al2O3
as the gate dielectric layer in future high performance devices.Comment: 3 figures. Applied Physics Letters, accepted for publicatio
Applications of the InChI in cheminformatics with the CDK and Bioclipse.
RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.BACKGROUND: The InChI algorithms are written in C++ and not available as Java library. Integration into software written in Java therefore requires a bridge between C and Java libraries, provided by the Java Native Interface (JNI) technology. RESULTS: We here describe how the InChI library is used in the Bioclipse workbench and the Chemistry Development Kit (CDK) cheminformatics library. To make this possible, a JNI bridge to the InChI library was developed, JNI-InChI, allowing Java software to access the InChI algorithms. By using this bridge, the CDK project packages the InChI binaries in a module and offers easy access from Java using the CDK API. The Bioclipse project packages and offers InChI as a dynamic OSGi bundle that can easily be used by any OSGi-compliant software, in addition to the regular Java Archive and Maven bundles. Bioclipse itself uses the InChI as a key component and calculates it on the fly when visualizing and editing chemical structures. We demonstrate the utility of InChI with various applications in CDK and Bioclipse, such as decision support for chemical liability assessment, tautomer generation, and for knowledge aggregation using a linked data approach. CONCLUSIONS: These results show that the InChI library can be used in a variety of Java library dependency solutions, making the functionality easily accessible by Java software, such as in the CDK. The applications show various ways the InChI has been used in Bioclipse, to enrich its functionality
New Notions and Constructions of Sparsification for Graphs and Hypergraphs
A sparsiļ¬er of a graph G (BenczuĀ“r and Karger; Spielman and Teng) is a sparse weighted subgraph Ė G that approximately retains the same cut structure of G. For general graphs, non-trivial sparsiļ¬cation is possible only by using weighted graphs in which diļ¬erent edges have diļ¬erent weights. Even for graphs that admit unweighted sparsiļ¬ers (that is, sparsiļ¬ers in which all the edge weights are equal to the same scaling factor), there are no known polynomial time algorithms that ļ¬nd such unweighted sparsiļ¬ers. We study a weaker notion of sparsiļ¬cation suggested by Oveis Gharan, in which the number of cut edges in each cut (S, ĀÆ S) is not approximated within a multiplicative factor (1 + Ē«), but is, instead, approximated up to an additive term bounded by Ē« times d Ā· |S| + vol(S), where d is the average
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