Number Of Level Changes Research Articles

Minimal cost multifactor experiments for agricultural research involving hard-to-change factors

Multifactor experiments are very common in agricultural research. Randomizing run orders in multifactor experiments often witness in large number of factorwise level changes which will increase the cost and time of the experiments. Minimal cost multifactor experiments are such experiments where the cost of the experiment is minimum which can be achieved by choosing a factorial run order where the total number of factor level change is minimum as cost of the experiment is directly proportional to the number of level changes of factors. Here, a method of constructing minimal cost 2-level multifactor experiments with minimum number of factorwise level changes has been proposed. As for a same factorial combination, there may exist more than one minimally changed factorial run order, an exhaustive search was also performed to obtain all possible minimally changed run order for two level multifactorial experiments with three factors. Due to restricted randomization, adaption of these run orders may witness the effect of systematic time trend. Hence, the usual method of analysis may not be a feasible solution due to lack of randomization. Here, the analytical procedure of experiments using minimal cost multifactorial run order has also been highlighted based on a real experimental data. The work has been carried out at ICAR-Indian Agricultural Statistics Research Institute, New Delhi during 2019-20. The data from the real experiment used for explaining the analysis procedure has been collected from Climate Change Facility of ICAR-Indian Agricultural Research Institute farm, New Delhi, India based on experiments conducted during 2014-15.

The Design and Analysis for the Icing Wind Tunnel Experiment of a New Deicing Coating

ABSTRACTA new kind of deicing coating is developed to provide aircraft with efficient and durable protection from icing-induced dangers. The icing wind tunnel experiment is indispensable in confirming the usefulness of a deicing coating. Due to the high cost of each batch relative to the available budget, an efficient design of the icing wind tunnel experiment is crucial. The challenges in designing this experiment are multi-fold. It involves between-block factors and within-block factors, incomplete blocking with random effects, related factors, hard-to-change factors, and nuisance factors. Traditional designs and theories cannot be directly applied. To overcome these challenges, we propose using a step-by-step design strategy that includes applying a cross array structure for between-block factors and within-block factors, a group of balanced conditions for optimizing incomplete blocking, a run order method to achieve the minimum number of level changes for hard-to-change factors, and a zero aliased matrix for the nuisance factors. New (theoretical) results for D-optimal design of incomplete blocking experiments with random block effects and minimum number of level changes are obtained. Results of the experiments show that this novel deicing coating is promising in offering both high efficiency of ice reduction and a long service lifetime. The methodology proposed here is generalizable to other applications that involve nonstandard design problems. Supplementary materials for this article are available online.

Minimally changed run sequences in factorial experiments

ABSTRACTRandomization of run sequences in factorial experiments may result in large number of changes in factor levels which will make the experimentation expensive, time-consuming and difficult. Experiments in which it is difficult to change the levels of factor(s) use of minimally changed run sequences may often be preferable to a random run sequence. In the present paper, we have developed method for obtaining minimally changed run sequences for factorial experiments. The general expression of factor-wise number of level changes for the developed minimally changed run sequences has also been obtained. A relationship has been established between the time count effect of a lower order factorial with minimally changed run sequences and that of a higher order factorial with minimally changed run sequences obtained through the lower order minimally changed run sequences. For providing a readymade solution to the end users, a SAS macro has also been developed for generating these minimally changed run sequences along with its parameters.

Minimum Cost Linear Trend Free Fractional Factorial Designs

Many fractional factorial experiments, especially those of exploratory type, are conducted sequentially in a specific run order. These experiments must be sequenced such that main effects and/or two-factor interactions are orthogonal (i.e., resistant) to the time trend or to any uncontrollable factor aliased with this trend. They must also be sequenced such that factors with expensive or difficult-to-vary levels are minimally varied during experimentation. This article employs the main effects–interactions assignment technique of Cheng and Jacroux (1988) and constructs a catalogue of minimum cost linear trend free regular 2 n−(n−k) fractional factorial designs of resolution at least 3. The construction is based on tabulating the complete 2 k factorial experiment such that main effects and interactions are in increasing number of level changes from 1 up to (2 k − 1), then selecting subtables involving the first n nonmain effects and assigning them to new two-level factors, where (2 k−1 − (k − 1) ≤ n ≤ 2 k...

Run orders for efficient two level experimental plans with minimum factor level changes robust to time trends

In this paper we construct run orders of orthogonal arrays with 12 ≤ n ≤ 28 runs and 4 ≤ q ≤ 6 factors that minimize the number of level changes of each factor. The corresponding orthogonal arrays can estimate a model with all main effects and their two factor interactions with the highest efficiency and also provide estimates of all main effects that are independent of linear and quadratic time (or position) trends. Some alternative efficient run orders are also presented when the estimation of two factor interactions is of experimental interest.

Minimum Aberration Two-Level Fractional Factorial Split-Plot Designs with Hard to Change Factors

In this article we will consider industrial experiments in which some experimental factors have hard to change levels and others have levels which are easy to change. In such situations, fractional factorial split plot designs are often used where the hard to change factors are included as a subset of the whole plot factors and the easy to change factors make up the subplot factors. Here we consider the problem of finding two-level split plot designs which have minimum aberration among those designs which also minimize the number of level changes for the hard to change factors.

A model‐based analysis of meander restoration

AbstractMeander reconnection is becoming a widely applied river restoration measure, aiming to enhance the ecological status of river systems. Based on a physical model study and a 3D hydrodynamic‐numerical simulation, the effects of different forms of meander reconnections on flow dynamics, water level and river morphology are investigated in present study including retention of the old main channel for flood protection when the bankfull discharge is exceeded. The distribution of total discharge between the reconnected meander bend and the flood channel during floods decreases flow velocity and bed shear stress and leads to aggradation. At higher discharges, the flow velocity decreases in the meander bend whereas it increases in the flood channel. The controlling parameter for flow diversion—hence for flow velocity and bed shear stress—is the elevation of the ramp diverting the flow.Using the hydrodynamic model RSim‐3D a particle tracing study simulated the trajectories of conservative particles at six vertical levels. The vertical movements of the particles on trajectories going through the reconnected meander were investigated by calculating the number of level changes of each particle. This novel approach in simulating particle movement in channels facilitating qualitative decision‐making in the framework of river restoration issues. In particular, it reveals information regarding heterogeneity and turbulence of the water and also nutrient movements under variable flow conditions and can thus help answer restoration‐related ecological questions. Copyright © 2009 John Wiley & Sons, Ltd.

MULTI-LEVEL FACTORIAL DESIGNS WITH MINIMUM NUMBERS OF LEVEL CHANGES

The order of experimental runs in a fractional factorial experiment is essential when the cost of level changes in factors is considered. The generalized foldover scheme given by [1]gives an optimal order to experimental runs in an experiment with specified defining contrasts. An experiment can be specified by a design requirement such as resolution or estimation of some interactions. To meet such a requirement, we can find several sets of defining contrasts. Applying the generalized foldover scheme to these sets of defining contrasts, we obtain designs with different numbers of level changes and then the design with minimum number of level changes. The difficulty is to find all the sets of defining contrasts. An alternative approach is investigated by [2]for two-level fractional factorial experiments. In this paper, we investigate experiments with all factors in slevels.

Development of a New Orientation Index for Airport Terminals

Some people have difficulty locating their destinations in airport terminals in spite of the availability of signs. The reasons for this wayfinding problem are numerous, and they include the complexity of the terminals as well as the wayfinding aids within them. An improved quantitative measure of human orientation called the visibility index (VI) is investigated. The effects of the number of signs or decision points and the number of level changes on visual access were investigated in an experiment in a complex building at The University of Calgary. A relationship between the slowness in reaching a destination, the number of decision points, and the number of level changes was developed. A survey of 32 common terminal activity centers was conducted. The ranks and weights of these activity centers were determined based on responses of airport users at three airports. The weight and the slowness factor were incorporated into the VI model, which was tested at Vancouver International Airport.

Two-level factorial designs with extreme numbers of level changes

The construction of run orders of two-level factorial designs with extreme (minimum and maximum) numbers of level changes is considered. Minimizing the number of level changes is mainly due to economic considerations, while the problem of maximizing the number of level changes arises from some recent results on trend robust designs. The construction is based on the fact that the $2^k$ runs of a saturated regular fractional factorial design for $2^k -1$ factors can be ordered in such a way that the numbers of level changes of the factors consist of each integer between 1 and $2^k -1$. Among other results, we give a systematic method of constructing designs with minimum and maximum numbers of level changes among all designs of resolution at least three and among those of resolution at least four. It is also shown that among regular fractional factorial designs of resolution at least four, the number of level changes can be maximized and minimized by different run orders of the same fraction.

Some results on two-level factorial designs with dependent observations

There are many situations in which observations in factorial experiments may be dependent. When this is so, run orders are needed that result in efficient estimates of contrasts. The Cheng and Steinberg reverse foldover algorithm, which gives a maximal number of level changes, is known to produce very efficient main-effects two-level designs using the D-criterion, but less is known about other designs, models and criteria. We present some further theoretical results, and give another statistic of importance in predicting efficiency under strong dependence. The theory is illustrated using some 16-run designs.

Time-trend free run orders with the minimum level changes

Time trend free run orders of factorial designs with the minimum number of level changes are very desirable in many applications. In this paper, a new construction technique is discovered to provide linear trend free run orders of sn factorial designs with the minimum number of level changes for all even positive integers s. Furthermore, when s is an odd positive integer, a run order of sn is constructed which has the minimum number of level changes, and whose time count does not increase along with n.

GABAergic drugs and sexual motivation, receptivity and exploratory behaviors in the female rat.

Female rats were allowed to pace sexual interactions in a bilevel chamber, where a sexually vigorous male was tethered to the bottom level. Exploratory behaviors (sniffing, rearing), locomotor activity (expressed as number of level changes and periods of inactivity) as well as items of sexual motivation (latency to descend to the male's level, approaches towards the male and genital exploration) were recorded. In addition, sexual receptivity was evaluated in a non-paced situation. A test for motor impairment was also performed. The GABA transaminase inhibitor gamma-acetylene GABA reduced exploratory behaviors at doses much lower than those needed to reduce receptivity. The GABA reuptake inhibitor SKF 100330A did not affect any behavior category at doses of 15 and 30 mg/kg, but had a sedative action at 60 mg/kg. This was shown as impaired motor coordination and an almost total absence of activity in the bilevel chamber. Receptivity was not impaired, however. The mixed GABAA/ GABAB agonist progabide reduced exploratory behaviors and receptivity without producing motor impairment at a dose of 400 mg/kg. The GABAA agonist THIP impaired motor coordination and reduced receptivity and exploratory behaviors at a dose of 10 mg/kg. A larger dose, 20 mg/kg, had a strong sedative action. Only a small proportion of the animals descended to the males level. The GABAB agonist baclofen reduced receptivity at a dose that had no effect on motor coordination or exploratory behaviors. None of the drugs had a specific effect on sexual motivation. Whenever behaviors reflecting motivation were reduced, there were also other behavioral effects indicative of sedation. These data show that GABA receptor agonists, particularly the GABAB agonist baclofen, reduce sexual receptivity at doses that have only slight effect on motor functions or exploratory behaviors. In contrast, non-specific enhancement of GABAergic activity by a transaminase or reuptake inhibitor have effects on motor functions and exploratory behaviors at doses much lower than those needed to reduce receptivity.

Appetitive sexual behavior in male rats: 1. The role of olfaction in level-changing behavior

Level-changing behavior is a form of anticipatory behavior of a male rat, when tested in a bilevel testbox. The male explores the testcage prior to introduction of a female. The female is introduced after 5 min. The number of level changes displayed by the male in this period reflects appetitive aspects of sexual behavior and it was suggested that analysis of this level-changing behavior may function as assessment of sexual motivation. In this study the increase of anticipatory level changes over repeated weekly tests was dependent upon (sexual) olfactory stimulation. The number of anticipatory level changes was reliably reduced by administration of the opioid antagonist naloxone, suggesting that endogenous opioids facilitate this behavior. These results suggest that the increase of anticipatory level changes over repeated tests is a response to olfactory stimuli and reflects appetitive aspects of sexual behavior, which are stimulated by endogenous opioids. These results are in accordance with the concept that analysis of anticipatory level-changing behavior can be used to assess sexual motivation.

Endogenous opioids are differentially involved in appetitive and consummatory aspects of sexual behavior of male rats.

The sexual activity of 40 male Wistar rats was tested weekly in a bilevel test chamber to evaluate the involvement of endogenous opioids in the appetitive and consummatory aspects of sexual behavior. It has been suggested that the increase of the anticipatory level-changing behavior over repeated testing, displayed before the introduction of a receptive female, is sexually motivated. Two doses of the opioid antagonist naloxone, 1 and 10 mg/kg, prevented the increase of the anticipatory level-changing over four repeated tests of sexually experienced rats without prior experience in the bilevel test chamber and decreased the number of level changes of rats displaying a high number of level changes. Analysis of the pattern of inhibition suggested that the lower dose of naloxone may reduce sexual reward and that, in addition, the higher dose may block the expression of motivation. In contrast, naloxone treatment facilitated the efficiency of the sexual performance, with less mounts and intromissions preceding ejaculation and a shorter ejaculation latency, implying an inhibitory role of endogenous opioids in the neural control of some aspects of sexual performance (e.g., ejaculatory threshold). These results suggest that endogenous opioids may increase sexual appetite and diminish sexual performance.

Binomial coding in distributed arbitration systems

A method for coding arbitration numbers in distributed arbitration schemes as used in Futurebus is proposed. The method is based on minimising the number of level changes in the arbitration process and allows one to reduce the arbitration time considerably. An algorithm for the construction of optimal codes for specified arbitration delay and number of arbitration lines is given.