3,589 research outputs found
Pressure anisotropy and small spatial scales induced by velocity shear
Non-Maxwellian metaequilibria can exist in low-collisionality plasmas as
evidenced by satellite and laboratory measurements. By including the full
pressure tensor dynamics in a fluid plasma model, we show that a sheared
velocity field can provide an effective mechanism that makes an initial
isotropic state anisotropic and agyrotropic. We discuss how the propagation of
magneto-elastic waves can affect the pressure tensor anisotropization and its
spatial filamentation which are due to the action of both the magnetic field
and flow strain tensor. We support this analysis by a numerical integration of
the nonlinear equations describing the pressure tensor evolution.Comment: 5 pages, 3 Figure
Piezoelectric effect and electroactive phase nucleation in self-standing films of unpoled PVDF nanocomposite films
Novel polymer-based piezoelectric nanocomposites with enhanced electromechanical properties open new opportunities for the development of wearable energy harvesters and sensors. This paper investigates how the dissolution of different types of hexahydrate metal salts affects β-phase content and piezoelectric response (d33) at nano-and macroscales of polyvinylidene fluoride (PVDF) nanocomposite films. The strongest enhancement of the piezoresponse is observed in PVDF nanocomposites processed with Mg(NO3)2·6H2O. The increased piezoresponse is attributed to the synergistic effect of the dipole moment associated with the nucleation of the electroactive phase and with the electrostatic interaction between the CF2group of PVDF and the dissolved salt through hydrogen bonding. The combination of nanofillers like graphene nanoplatelets or zinc oxide nanorods with the hexahydrate salt dissolution in PVDF results in a dramatic reduction of d33, because the nanofiller assumes a competitive role with respect to H-bond formation between PVDF and the dissolved metal salt. The measured peak value of d33reaches the local value of 13.49 pm/V, with an average of 8.88 pm/V over an area of 1 cm2. The proposed selection of metal salt enables low-cost production of piezoelectric PVDF nanocomposite films, without electrical poling or mechanical stretching, offering new opportunities for the development of devices for energy harvesting and wearable sensors
"Magneto-elastic" waves in an anisotropic magnetised plasma
The linear waves that propagate in a two fluid magnetised plasma allowing for
a non-gyrotropic perturbed ion pressure tensor are investigated. For
perpendicular propagation and perturbed fluid velocity a low frequency
(magnetosonic) and a high frequency (ion Bernstein) branch are identified and
discussed. For both branches a comparison is made with the results of a
truncated Vlasov treatment. For the low frequency branch we show that a
consistent expansion procedure allows us to recover the correct expression of
the Finite Larmor Radius corrections to the magnetosonic dispersion relation.Comment: 16 pages, 9 figure
Emisi Gas Metana dan Karbon Dioksida pada Proses Pengolahan Limbah Cair Kelapa Sawit
Purpose: The purpose of this study was to know, calculate and evaluate the concentration of methane gas and carbon dioxide produced in each wastewater treatment plant (WWTP) pond.Method: This research was a qualitative research, using case study design and explanatory approach. The object of this research was the emission of methane gas and carbon dioxide emitted from 12 WWTP ponds.Results: The highest COD and BOD decrement occurred in pond 4 of 39% COD and 61.2% BOD. The highest total methane gas emission was 1.49 x 109 kg hours-1 (1.49 x 106 tons hour-1) occurring in the morning, while the highest total carbon dioxide emission was 2.59 x 109 kg per hour (2.59 x 106 ton hour-1). Conclusion: The concentrations of methane and carbon dioxide gas produced by each WWTP pool varied greatly depending on temperature, residence time and the amount of mud. Methane gas emissions and carbon dioxide emissions occurred in each WWTP pool with the highest methane gas emission value occurring in pond 3 in the afternoon at 356,64 x 106 mg m-2minute-1 and the highest carbon dioxide emissions occur in pond 3 in the afternoon at 402.145 x 106 mg m-2minute-1. The decrease of COD value in whole anaerobic pool was 52,1% and the decrease of COD value in aerobic pool was 27,2%
THE DETERMINATION OF LANDFILL (TPA) ALTERNATIVE LOCATION IN WEST TULANG BAWANG DISTRICT OF LAMPUNG PROVINCE
West Tulang Bawang is one of the new regencies in Indonesia which was a new expanded area that continues to grow. It is followed by population growth rates resulting in increased volume of waste. The landfill (TPA) is an important component of any waste management system. A good waste has several characteristics. To ensure the appropriate selected land, a systematic process must be developed and followed.The study of the selection of the landfill (TPA) is aimed at finding feasible area as the location of the landfill, so that the allocation of the new landfill will be in accordance with local policies in regional spatial planning and meet the criteria of ISO No. 19-3241-1994. The role of Geographic Information System (GIS) in the management of solid waste is important because many aspects of planning and operations are highly dependent on the spatial data. The landfill selection process consists of three stages of filtering, i.e., the feasibility of the environment by utilizing Geographic Information System (GIS) to map the location of viable landfill, regional filtering phase based on the regional policy and the elimination filtering using SNI 19-3241-1994.The results of the study showed that with an estimated population in 2033 which is 330 807 people, the amount of waste that will go to the landfill through the 3R principle reached 309.36 m3 / day or 61.87 tons / day so that the area of the required land for the sanitary landfill pattern with a 20 year planning is 17.70 Ha. The alternative location was selected by with a priority level which is located on the Panaragan Jaya Utama of Central Tulang Bawang sub-district with a land of 99.68 hectares, Tulang Bawang village districts Panaragan Central with a land area of 136.26 ha and the Kagungan Ratu village of Tulang Bawang sub-district of 74 , 65 Ha
Study of chromium removal from wastewater using SSF-CW model: comparison between physical adsorption by coal CFA and phytoremediation by vetiver grass (Vetiveria Zizanioides L)
The study aims to compare the effectiveness of chromium removal from water using adsorption by coal fly ash (CFA) and phytoremediation by vetiver grass (Vetiveria zizanioides L) as well as a combination of both CFA and vetiver grass. The experiment was carried out in four different reactors, having size of 100 cm (length) x 60 cm (wide) x 80 cm (height). One reactor was filled with gravel and CFA, without vetiver grass (RI), while another one was filled with gravel and vetiver grass, without CFA (RIV). The other two reactors were filled with gravel, CFA, and vetiver grass with the mass ratio of gravel/CFA of (25:2) and (25:1), denoted as RII and RIII, respectively. Fifty (50) L of synthetic wastewater containing 14.612 ppm of chromium was filled into the reactors and continuously recirculated for 15 days. Chromium accumulation in CFA and plants was analyzed on day 15. The results of plant development are indicated by the presence of new shoots and roots that grow during phytoremediation processes. In addition, there was an increase in weight and number of vetiver stems indicating the persistency of vetiver grass in such a harsh wastewater condition. The removal of Cr from wastewater in RI, RII, RIII and RIV at days 15 were 81%, 93.2%, 85.8% and 75.7%, respectively. It can be concluded that: (1) vetiver grass (Vetiveria zizanioides L) has high potential as phytoremediator plant, (2) Chromium adsorption by CFA plays important role in Cr removal from wastewater, and (3) combination of adsorption by CFA and a phytoremediation by vetiver grass significantly increases the removal of chromium from wastewater
Efficient algorithms to discover alterations with complementary functional association in cancer
Recent large cancer studies have measured somatic alterations in an
unprecedented number of tumours. These large datasets allow the identification
of cancer-related sets of genetic alterations by identifying relevant
combinatorial patterns. Among such patterns, mutual exclusivity has been
employed by several recent methods that have shown its effectivenes in
characterizing gene sets associated to cancer. Mutual exclusivity arises
because of the complementarity, at the functional level, of alterations in
genes which are part of a group (e.g., a pathway) performing a given function.
The availability of quantitative target profiles, from genetic perturbations or
from clinical phenotypes, provides additional information that can be leveraged
to improve the identification of cancer related gene sets by discovering groups
with complementary functional associations with such targets.
In this work we study the problem of finding groups of mutually exclusive
alterations associated with a quantitative (functional) target. We propose a
combinatorial formulation for the problem, and prove that the associated
computation problem is computationally hard. We design two algorithms to solve
the problem and implement them in our tool UNCOVER. We provide analytic
evidence of the effectiveness of UNCOVER in finding high-quality solutions and
show experimentally that UNCOVER finds sets of alterations significantly
associated with functional targets in a variety of scenarios. In addition, our
algorithms are much faster than the state-of-the-art, allowing the analysis of
large datasets of thousands of target profiles from cancer cell lines. We show
that on one such dataset from project Achilles our methods identify several
significant gene sets with complementary functional associations with targets.Comment: Accepted at RECOMB 201
Identifikasi kepekaan operasi reaktor alir tangki berpengaduk untuk reaksi paralel melalui model matematik
ABSTRACT:
A Continuous stirred tank reactor (CSTR) has been simulated matematically. The reactor is used to process a paralel reaction, A to be B and C. By the use of mass and energy balance, the process could be formulated in four nonliniear ordinary deferential equations. Because of their reaction characteristics, operating condition and multiplicity has to be investigated. Operating temperature was chosed based on conversion, productivity, and selectivity. Normal feed flow rate, which is represented in Damkohler number, was taken to avoid multiplicity.
The sensivity of CSTR was identified by using all possible disturbances on the process, i.e. feed flow rate, feed temperature, and feed concentration. Computations was done both for nonlinier differential equations and linierized arround steady state differential equations. The simulation shows
that their result are different significantl
"Ideal" tearing and the transition to fast reconnection in the weakly collisional MHD and EMHD regimes
This paper discusses the transition to fast growth of the tearing instability
in thin current sheets in the collisionless limit where electron inertia drives
the reconnection process. It has been previously suggested that in resistive
MHD there is a natural maximum aspect ratio (ratio of sheet length and breadth
to thickness) which may be reached for current sheets with a macroscopic length
L, the limit being provided by the fact that the tearing mode growth time
becomes of the same order as the Alfv\`en time calculated on the macroscopic
scale (Pucci and Velli (2014)). For current sheets with a smaller aspect ratio
than critical the normalized growth rate tends to zero with increasing
Lundquist number S, while for current sheets with an aspect ratio greater than
critical the growth rate diverges with S. Here we carry out a similar analysis
but with electron inertia as the term violating magnetic flux conservation:
previously found scalings of critical current sheet aspect ratios with the
Lundquist number are generalized to include the dependence on the ratio
where de is the electron skin depth, and it is shown that there are
limiting scalings which, as in the resistive case, result in reconnecting modes
growing on ideal time scales. Finite Larmor Radius effects are then included
and the rescaling argument at the basis of "ideal" reconnection is proposed to
explain secondary fast reconnection regimes naturally appearing in numerical
simulations of current sheet evolution.Comment: 15 pages, 3 Figures, 1 Tabl
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