Effect Of Simultaneous Variation Research Articles

The impact of the varying nutrient concentrations on the enhanced biological phosphorus removal performance and functional phosphorus-accumulating and denitrifying genes in an anaerobic–aerobic–anoxic sequencing batch reactor

The denitrifying phosphorus-accumulating organisms (DPAOs) were extensively focused in the past years due to their high efficiencies in simultaneous removal of phosphorus (P) and nitrogen (N) in wastewater treatment. However, it is not clear how this group of bacteria evolve along with the operation process of a specific wastewater treatment system. Here, it is firstly investigated that the effects of simultaneous variations in chemical oxygen demand (COD), P, and N concentrations on enhanced biological phosphorus removal and phosphorus accumulating (PAOs) and DPAOs in an anaerobic–aerobic–anoxicSBR. The results showed that P and N removal ratios were 83.10 ± 6.72% and 64.21 ± 7.10%, 90.38 ± 3.63% and 84.52 ± 4.91%, 78.82 ± 8.78% and 78.71 ± 3.98% corresponding to the SBR operation process of phases I, II and III respectively. The potential PAOs and DPAOs (such as genera Thauera and Dechloromonas ) were clearly enriched at different operation phases, especially at phase II. Q-PCR and correlation analysis indicated that phosphorus accumulating-related ppk1 genes and denitrifying-related genes coexisted in the SBR and their contents varied with influent COD, P, and N concentrations. Moreover, ppk 1 genes clade IIC/IIF and denitrifying-related genes nir K were highly correlated in the SBR. Therefore, simultaneous variations in nutrient concentrations significantly affected the abundance and distribution of functional bacteria and genes related to P and N removal. The results are valuable in N and P removal of practical wastewater treatment engineering

Combined effect of external damper and cross-tie on the modal response of hybrid two-cable networks

Combining external dampers and cross-ties into a hybrid system to control bridge stay cable vibrations can address deficiencies associated with these two commonly used vibration control solutions while retaining their respective merits. Despite successful implementation of this strategy on a few cable-stayed bridges, behavior of such a structural system is still not fully understood. In the current study, an analytical model of a hybrid system consisting of two parallel taut cables interconnected by a transverse linear flexible cross-tie, with one cable also equipped with a transverse linear viscous damper close to one end support, is developed. The proposed model is validated by an experimental work in the literature and an independent numerical simulation. A parametric study is conducted to comprehend the impact of main design parameters on the performance of a hybrid system in terms of the in-plane frequency, the damping and the degree of mode localization of the system's fundamental mode. In addition, the concept of isoquant curve is applied not only to appreciate the effect of simultaneous variation in main design parameters on the modal behavior of a hybrid system, but also to identify the optimal ranges of these parameters to achieve the required cable vibration control effect.

Effect of the Simultaneous Variation in Blade Root Chord Length and Blade Taper on Helicopter Flight Control Effort

In this study, the effect of simultaneous variation in blade root chord length and blade taper on the control effort of helicopter flight control system (i.e., FCS) of a helicopter is investigated. Therefore, helicopter models (i.e., complex, control-oriented, and physics-based models) including the main physics and essential dynamics are used. The effect of simultaneous variation in the blade root chord length and blade taper (i.e., in both chordwise and lengthwise directions dependently) on the control effort of an FCS of a helicopter and also on the closed-loop responses is studied. Comparisons in terms of the control effort and peak values with and without variations in the blade root chord and blade taper changes are carried out. For helicopter FCS variance-constrained controllers, specific output variance-constrained controllers are beneficial.

Effect of simultaneous variation in temperature and ammonia concentration on percent fertilization and hatching in Crassostrea ariakensis

The combined effects of temperature and ammonia concentration on the percent fertilization and percent hatching in Crassostrea ariakensis were examined under laboratory conditions using the central composite design and response surface methodology. The results indicated: (1) The linear effects of temperature and ammonia concentration on the percent fertilization were significant (P<0.05), and the quadratic effects were highly significant (P<0.01). The interactive effect between temperature and ammonia concentration on the percent fertilization was not significant (P>0.05). (2) The linear effect of temperature on the percent hatching was highly significant (P<0.01), and that of ammonia concentration was nonsignificant (P>0.05). The quadratic effects of temperature and ammonia concentration on the percent hatching were highly significant (P<0.01). The interaction on the percent hatching was not significant (P>0.05). Temperature was more important than ammonia in influencing the fertilization and hatching in C. ariakensis. (3) The model equations of the percent fertilization and hatching towards temperature and ammonia concentration were established, with the coefficients of determination R2=99.4% and 99.76%, respectively. Through the lack-of-fit test, these models were of great adequacy. The predictive coefficients of determination for the two model equations were as high as 94.6% and 98.03%, respectively, showing that they could be used for practical projection. (4) Via the statistical simultaneous optimization technique, the optimal factor level combination, i.e., 25°C/0.038mgmL−1, was derived, at which the greatest percent fertilization 95.25% and hatching 83.26% was achieved, with the desirability being 97.81%. Our results may provide advantageous guidelines for the successful reproduction of C. ariakensis.

A Statistical Approach for Estimation of Fusion Behavior of Alumino-Thermic Ferrochrome Slags

Effects of simultaneous variations of Al2O3/CaO ratio, and MgO and CaF2 contents, on the fusion behavior of synthetic alumino-thermic ferrochrome slags are systematically measured using a hot-stage-microscope in accordance with German standard 51730. Empirical equations are developed for the prediction of the softening temperature (ST), liquidus/hemispherical temperature (HT), and flow temperature (FT), in terms of aforementioned variables using Factorial Design Technique. To verify the predicted equations, further groups of synthetic slags are prepared in the laboratory using pure oxides, and the characteristic temperatures of these slags are measured in the same manner using hot-stage microscope. It is observed that within the range of variables examined, equations developed render the best fit for HT, the next best fit for FT, and somewhat good fit for ST.

Damage Analyses of Adhesively Bonded Single Lap Joints Due to Delaminated FRP Composite Adherends

Three-dimensional non-linear Finite Element Analyses (FEA) due to an in-plane loading have been performed to evaluate the out-of-plane normal and shear stresses over the overlap region of a Single Lap Joint (SLJ) on different surfaces. These surfaces have been considered as; (i) two interfacial surfaces between the adherends and the adhesive layer, (ii) the mid-surface of the adhesive layer and (iii) two surfaces beneath the surface ply of both the adherends adjacent to the adhesive layer. The critical locations of onset of adhesion, cohesion and delamination failures on the above mentioned surfaces of the SLJ have been determined using suitable damage criteria. A comparative study due to adhesion, cohesion and delamination failures in the SLJ with Fiber Reinforced Polymeric (FRP) composite adherends have been presented. The effects of simultaneous variations of the delamination positions on the out-of-plane peel and shear stress components have been studied by pre-embedding the delamination damages at the critical locations in both the adherends. It has been observed that the possibilities of onset of cohesion failures in the adhesive layer are higher compared to the adhesion and delamination failures. The detailed analyses showed that secondary peaks of out-of-plane stress components (σ z , τ yz and τ xz ) on the mid surface of the adhesive layer appeared at the locations closer to the delamination fronts due to pre-embedded delamination damages. The highest stress magnitudes on the overlap edge of the SLJ have been reduced significantly when the centers of the delamination damages are exactly aligned with the overlap ends of the joint. No significant variations of stress magnitudes have been noticed either when the delaminations are pre-embedded outside the overlap regions or when the delamination damages are completely entrapped within the overlap region.

Optimisation of freezing process with pressure steaming of potato tissues (cvMonalisa)

Response surface methodology (RSM) was used for determining optimum conditions of the freezing process on pectinesterase (PE) activity, rheological parameters and textural properties in potato tissues. In the process of production of frozen potatoes, the second step of the stepwise blanching prior to freezing was considered as a fixed factor and performed at 97 °C for 2 min as well as the freezing rate in the freezing step itself, which was carried out at -2 °C min -1 . The effects of variation in levels of temperature (57.93-72.07°C) and time (15.86-44.14 min) in the first blanching step on the PE activity were studied using a central composite rotatable design. A Box-Behnken factorial design was used to investigate the effects of simultaneous variation of temperature (60-70 °C) and time (20-40min) in the first blanching step and steaming temperature (112-122°C) and time (1-3 min) on rheological parameters and textural properties. Blanching temperature was the independent variable that most influenced either enzymatic activity or rheological parameters. Stationary points showing maximum PE activity had critical temperature and time values of 64.22°C and 29.37min before freezing and 64.39°C and 28.02min after freezing and steaming of the tissues, and these values were very close to those obtained for some creep compliance parameters. Results show a high correlation between increases in PE activity and tissue firmness below optimum experimental freezing conditions, proving the role of the enzyme as one of the main contributors to the firmness which determines the textural quality of frozen potato tissues.

The QP Triangle: A Graphical Method for Bias Design

A graphical design procedure is presented based upon a QP triangle for the design of bipolar transistor (BJT) bias circuits. The design technique stresses quiescent point (QP) location on the IC-VCE characteristics and considers the effects of simultaneous variations in the BJT parameters hFE, VBE, and ICO upon QP location. The QP triangle method is developed for the standard one-battery BJT CE stage discussed in many introductory electronic circuits textbooks. The QP triangle method is applied to a specific CE stage which has to meet certain design specifications. One important specification is that the circuit must operate over the temperature range 25-100°C with silicon N-P-N BJT's having values of h<FE (25°C) > 40 and hFE 100°C) < 200. The available tradeoffs between the peak-to-peak voltage Vpp and the current gain AI are stressed and the best available design is selected. The performance of the selected design was simulated on a digital computer and measured in the laboratory. Both the computer simulation and the experiment are in good agreement with the design. The QP triangle method has been used in an introductory electronic circuits course with success for several years. Students understand this graphical design procedure and are able to apply it. It is recommended for beginning electronics students. An interactive computer program AMPDSN to aid students and instructors design the standard one-battery BJT CE stage is also described. An algorithm based upon the QP triangle is used. The program language is Basic.

Some Effects of Simultaneous Variation in Salinity, Temperature and Dissolved Oxygen on the Resistance of Young Coho Salmon to A Toxic Substance

Median resistance times of juvenile coho salmon (Oncorhynchus kisutch) acclimated to fresh water at 12 °C were investigated at 3 mg/l of sodium pentachlorophenate over combinations of levels of salinity, temperature and dissolved oxygen using factorial schemes developed by Box and associates. For the relationship:[Formula: see text]a true response ς is regarded as a function of combinations of levels of k quantitative factors x1, x2, x3, …, xk. The relationship was approximated by a polynomial in x for the three coded factors—salinity (x1), ‰; temperature (x2), °C; and dissolved oxygen (x3), mg/l. The experimental data were fitted to a second-order polynomial:[Formula: see text]This was transformed to its canonical form, from which ellipsoidal response surfaces were constructed. Alternative levels of salinity, temperature and dissolved oxygen were computed for general evaluation of the manner in which these variables altered the response to the pentachlorophenate. A maximum response time was computed for the response surfaces, associated with levels of the three variables at 17.68‰ salinity, 4.86 °C and 7.66 mg/l, O2.The use of multivariate experimental techniques is discussed as a means of considering the significance of alteration in the levels of associated environmental factors in evaluation of experimental or environmental situations involving water quality alteration.