Performance Index PI Research Articles

Textile study courses – evaluation of student performance over one complete decade

The success of students and their performance are influenced by manifold parameters. The current study focusses especially on the correlation between study duration and the student performance. Investigated are the numbers of two textile related courses (bachelor and master) over the complete time frame of one decade. Data of more than 800 students are considered. Data evaluation is done with the final marks of the students and by using a calculated value – the student performance index PI. Especially discussed is the behavior of long-time students needing more than the double of the regular study duration. In this study only results of students are discussed which successfully finished the study course with a degree. Students leaving without a degree are not considered. For the bachelor course a correlation of their final grades with larger study duration can be determined. In contrast, for the master course nearly no influence of the study duration on the student performance is determined. A possible explanation for these different results can be discussed with the different reasons for longer study duration. For master course it is obviously the situation that the studying is combined with part-time or even full-time jobs. This combination of job and study course leads even for excellent students to prolonged study duration. With this background, for future developments a special designed part time master study course should be developed and offered for students who like the combination of a job carrier with gaining simultaneously a master degree.

Comparative Approach on the Effects of Soil Amendments and Controlled-Release Fertilizer Application on the Growth, Nutrient Uptake, Physiological Performance and Fruit Quality of Pepper (Capsicum annuum L.) Plants

Under the economic pressure from the increase of fertilizers’ prices due to the recent energy crisis, more efforts are needed to search for alternative and cheaper sources of nutrients for crops. The purpose of our study was to compare the effects of manure and inorganic amendments’ application to those derived from the application of a controlled-release fertilizer (CRF) on the growth, nutrition, physiology and fruit quality of pepper plants. For that reason, zeolite (ZEO) and vermiculite (VER) were applied either independently, or in combination between them, or with manure (MAN), in a pot experiment. Insignificant differences for plant growth among the treatments were recorded, while higher foliar N, Mg and Mn concentrations were determined in CRF. In contrast, a significantly higher K uptake was recorded in the ZEO and VER + ZEO treatments; the highest leaf P levels (0.47 and 0.44% D.W.) were recorded in the MAN + VER and ZEO treatments, respectively. The optimum photosynthetic II (PSII) performance was observed in the VER and in the MAN + ZEO (based on the performance index—PI) treatments. The highest stomata opening was found in the CRF treatment, while the photosynthetic rate of pepper plants showed its maximum values both in the CRF and VER treatments. Finally, fruit quality (as indicated by total soluble solids, total phenols and antioxidant activity—FRAP) was significantly influenced by treatment. In conclusion, significant differences in the growth, nutrition and physiological performance of pepper plants between soil amendments’ application (inorganic, such as zeolite and vermiculite, and organic, such as manures) and CRF application were recorded; thus, these amendments should be more thoroughly studied in future projects to investigate if they could partially decrease high inorganic fertilization rates in Capsicum annuum L.

Combined effects of NaCl and Cd2+ stress on the photosynthetic apparatus of Thellungiella salsuginea

Plants show complex responses to abiotic stress while, the effect of the stress combinations can be different to those seen when each stress is applied individually. Here, we report on the effects of salt and/or cadmium on photosynthetic apparatus of Thellungiella salsuginea. Our results showed a considerable reduction of plant growth with some symptoms of toxicity, especially with cadmium treatment. The structural integrity of both photosystems (PSI and PSII) was mostly maintained under salt stress. Cadmium induced a considerable decrease of both PSI and PSII quantum yields and the electron transport rate ETR(I) and ETR(II) paralleled by an increase of non-photochemical quenching (NPQ). In addition, cadmium alone affects the rate of primary photochemistry by an increase of fluorescence at O-J phase and also the photo-electrochemical quenching at J-I phase. A positive L-band appeared with (Cd) treatment as an indicator of lower PSII connectivity, and a positive K-band reflecting the imbalance in number of electrons at donor and acceptor side. In continuity to our previous studies which showed that NaCl supply reduced Cd2+ uptake and limited its accumulation in shoot of divers halophyte species, here as a consequence, we demonstrated the NaCl-induced enhancement effect of Cd2+ toxicity on the PSII activity by maintaining the photosynthetic electron transport chain as evidenced by the differences in ψO, φEo, ABS/RC and TR0/RC and by improvement of performance index PI(ABS), especially after short time of treatment. A significant decrease of LHCII, D1 and CP47 amounts was detected under (Cd) treatment. However, NaCl supply alleviates the Cd2+ effect on protein abundance including LHCII and PSII core complex (D1 and CP47).

Comparative analysis of salt stress, duration and intensity, on the chloroplast ultrastructure and photosynthetic apparatus in Thellungiella salsuginea

Salinity is one of the most important abiotic stress affecting plant growth and productivity worldwide. Photosynthesis, together with cell growth, is among the primary process affected by salinity. Here, we report the effects of salt stress on photosynthesis in the model halophyte Thellungiella salsuginea. Plants were grown in hydroponic system and then treated for 2 weeks with different NaCl concentrations (0, 100, 200 and 400 mM). Leaf analysis using both photonic and transmission electron microscopes showed some changes in mesophyll cell organization, including shape and dimension. Under high NaCl concentration (400 mM) a swelling of thylakoids and starch accumulation was also observed. The obtained results also showed a change in the photosynthetic efficiency of both photosystems (PSI and PSII), depending on both NaCl concentrations and duration of the stress treatment. Under moderate salinity (100 and 200 mM NaCl) no significant variation was observed in PSI and PSII yield parameters. Chlorophyll a fluorescence transient showed some variations in OJ, JI and IP phases under salt stress depending also on NaCl levels and the duration of stress. Under high salinity PSII donor side was affected as well as quantum yield of PSI which also showed a donor side limitation. A significant decrease on quantum yields Y(I) and Y(II) under high salt treatment (400 mM NaCl) for prolonged period of time (15 days) was observed. The decrease of these parameters was quantitatively compensated by a corresponding increase of energy thermal dissipation Y(NPQ) in photosystem II and a increase in the Y(ND) in PSI. Analysis of derived parameters from the OJIP transient curve revealed that ABS/RC decreased under NaCl treatment by reason of the increase in size of antenna of active reaction centers. An increase in the performance index PI(ABS), a slight decrease in the rate of DIO/RC, TRO/RC and the level of electron transport per PSII RC (ETO/RC) were observed during the first days of salt stress treatment reflecting a high PSII efficiency.

Plant functional traits – fixed facts or variable depending on the season?

Traits are widely used to detect and explain responses of ecosystem processes to environmental changes. Various studies use trait data from databases, often providing one value per trait and species, neglecting intraspecific trait variability along spatio-temporal gradients. Handbooks for standardized trait measurements claim that traits should be measured at an ‘optimal’ stage, which is typically defined to be reached when the plants are in full blossom. However, it is unclear whether this method is appropriate. The main aim of this study was to quantify the extent to which trait values vary with season and phenology, a type of variation that has been overlooked so far relative to other sources of intraspecific variation. Further, we aimed to investigate whether species rankings remain consistent throughout the year. From April to November 2012, we monitored seven leaf traits [specific leaf area SLA, leaf dry matter content, chlorophyll fluorescence parameters (Fv/Fm, performance-index PI], stomatal density, stomatal size and the stomatal pore area index SPI) of 15 summer green woody species weekly under controlled conditions. In parallel, we recorded phenological stages. The results showed that all traits varied significantly throughout the year in a species-specific manner. We detected trait relationships with vegetative but not with flowering phenology. Species rankings were inconsistent throughout the season in all traits. We concluded that the seasonal timing of trait measurements is crucial. Most notably SLA, Fv/Fm and stomatal size were the most robust traits in terms of small intraspecific and large interspecific variation and showed largely consistent species rankings across seasons.

Performance index assessment of intelligent computing methods in EMG-based neuromuscular diseases

In the medical systems, there is a lack of determining and assessing the performance measure of the intelligent computing methods ICM deployed in the diagnosis of bioelectric signals EEG/EMG/ECG-based diseases. There have been few attempts for performance measure of mathematical models in medical computing. In this paper, we have developed a heuristic method for the assessment of performance measure in the diagnosis of EMG-based neuromuscular diseases. Firstly, we review the various ICM then we perform qualitative assessment of mathematical, algorithmic and heuristic content, data acquisition cost as well as medical consultancy cost of various parameter of EMG and non-EMG psychological, cognitive and muscular. The computational overhead CO of EMG parameters, overall computational overhead OCO and clinical consultancy cost CC are determined. Finally, performance index PI is computed based on the two overheads and clinical cost. A graph showing the comparative view of CO of EMG parameters, OCO and CC is plotted and PI is shown for all the methods.

Interactive effects of drought, elevated CO 2 and warming on photosynthetic capacity and photosystem performance in temperate heath plants

Increased temperature, atmospheric CO 2 and change in precipitation patterns affect plant physiological and ecosystem processes. In combination, the interactions between these effects result in complex responses that challenge our current understanding. In a multi-factorial field experiment with elevated CO 2 (CO2, FACE), nighttime warming (T) and periodic drought (D), we investigated photosynthetic capacity and PSII performance in the evergreen dwarf shrub Calluna vulgaris and the grass Deschampsia flexuosa in a temperate heath ecosystem. Photosynthetic capacity was evaluated using A/ C i curves, leaf nitrogen content and chlorophyll- a fluorescence OJIP induction curves. The PSII performance was evaluated via the total performance index PI total, which integrates the function of antenna, reaction centers, electron transport and end-acceptor reduction according to the OJIP-test. The PSII performance was negatively influenced by high air temperature, low soil water content and high irradiance dose. The experimental treatments of elevated CO 2 and prolonged drought generally down-regulated J max, V cmax and PI total. Recovery from these depressions was found in the evergreen shrub after rewetting, while post-rewetting up-regulation of these parameters was observed in the grass. Warming effects acted indirectly to improve early season J max, V cmax and PI total. The responses in the multi-factorial experimental manipulations demonstrated complex interactive effects of T × CO2, D × CO2 and T × D × CO2 on photosynthetic capacity and PSII performance. The impact on the O–J, J–I and I–P phases which determine the response of PI total are discussed. The single factor effects on PSII performance and their interactions could be explained by parallel adjustments of V cmax, J max and leaf nitrogen in combination. Despite the highly variable natural environment, the OJIP-test was very robust in detecting the impacts of T, D, CO2 and their interactions. This study demonstrates that future climate will affect fundamental plant physiological processes in a way that is not predictable from single factor treatments. The interaction effects that were observed depended upon both the growth strategy of the species considered, and their ability to adjust during drought and rewetting periods.

Improved UV-B screening capacity does not prevent negative effects of ambient UV irradiance on PSII performance in High Arctic plants. Results from a six year UV exclusion study

Long-term responses of ambient solar ultraviolet (UV) radiation were investigated on Salix arctica and Vaccinium uliginosum in a High Arctic heath ecosystem in Zackenberg, northeast Greenland. Over a period of six years, UV exclusion was conducted in the growing season by means of filters: 60% UV-B reduction, 90% UV-B + UV-A reduction, UV transparent filter control, and an open control without filter. Plant responses were evaluated using specific leaf area, leaf content of UV-B absorbing compounds and PSII performance parameters derived from chlorophyll- a fluorescence induction curves. Based on the JIP-test, we calculated the total performance index PI total, which includes the integrating antennae, the PSII reaction center, intersystem electron transport and reduction of PSI end acceptors-dependent parameters. In both species, UV exclusion significantly decreased the content of UV-B-absorbing compounds. Salix increased its specific leaf area, while Vaccinium decreased it. UV exclusion increased the PI total in both species during all six years of experimentation. This response was governed by a significantly decreased RC/ABS, a marginally non-significant increased ET o/TR o and a significantly increased TR o/ABS = F V/ F M and RE o/ET o. These results demonstrate the current level of ambient UV-B to decrease PSII performance significantly in these High Arctic plants. It appears that the two plant species both have improved their UV-screening capacity, but through different strategies, although this did not sufficiently prevent negative effects of the ambient UV radiation. We argue the decreased PSII performance to be part of a response decreasing plant carbon uptake. We speculate the negative effects on PSII performance mediated by ambient UV irradiance to be present in years where warming induces early snowmelt, exposing the vegetation to high spring UV-B, and to be present in the future to the degree the ozone layer is not fully recovered.

Fast chlorophyll fluorescence transient and nitrogen fixing ability of chickpea nodulation variants

High nodulating (HN) selections of the cultivars ICC 4948 and ICC 5003 had the highest nodule number and nodule dry mass followed by low nodulating (LN) selections of the same cultivar. Both non-nodulating (NN) selections of cv. ICC 4993 and ICC 4918 did not show any nodule. Using N-difference method the HN selection of cv. 1CC 4948 was able to meet 73 % of its demand of N through biological fixation of N2 [P(fix)], while 27 % of N demand was met by uptake from the soil, whereas its LN selection was able to meet only 54 % of its demand of N through biological fixation of N2. Similarly in cv. ICC 5003 HN and LN selections the P(fix) was 76 and 64 %, respectively. Fast chlorophyll (Chl) fluorescence transient data analysis showed that performance index PI(abs) was 62.0 in cv. ICC 4948 HN selection and 44.5 in its respective LN selections. Corresponding values for cv. ICC 5003 were 32.4 and 28.4. In NN selections of ICC 4993 and ICC 4918 it was 12.6 and 30.7, respectively. Structure function index of the plants SFI(abs) and driving force for photosynthesis (DF) were highest in the HN selections followed by LN selections and lowest in the NN selections. The total uptake of N by chickpea plants was significantly and positively correlated with the density of reaction centres ABS/CS0, TR0/CS0, and DI0/CSM, whereas total N uptake by chickpea seeds was significantly positively correlated with N and TR0/CS0. The percentage of P(fix) was highly significantly positively correlated with N, the so-called turnover number which indicates how many times QA has been reduced in the time span from 0 to tFmax and TR0/CS0. Fast Chl a fluorescence measurement can be used as a model system to assess the N fixation ability in chickpea.

Distribution system reconfiguration to reduce resistive losses

Abstract This paper presents an efficient algorithm to solve the reconfiguration problem by a switching operation to reduce the power loss of distribution systems. By utilizing the proposed heuristic rules and performance index PI which represent the loss reduction capability of the switching operation, a better network configuration is obtained. the PI ranking algorithm based on the linearized load flow model is applied to evaluate the PI reduction for each feasible switching operation and the PI ranking algorithm is then used to find the switching operation to be executed to reach the minimum system loss. A two-stage searching approach to the switching operation is proposed in this paper. The evaluation function of each tie switch is estimated and a depth-first search is used to find all possible switching operations. A performance index is then used to evaluate the loss-reduction capability of each feasible switching candidate. Two practical distribution systems of Taiwan Power Company (Taipower) have been selected for computer simulation to demonstrate the effectiveness of the proposed method.

Design of Digital Control Systems with Finite Setting Time Via Nonlinear Programming Approach

In this paper, a deadbeat-model performance index is obtained by using the deadbeat model which plays the role of the ideal specification of the desired system performance. Another two performance indices are also defined such that a final performance index PI is formulated. The parameter optimization technique utilizing this performance index PI for the design of digital control systems with finite settling time is developed. The Quasi-Newton unconstrained nonlinear programming algorithm is applied to evaluate the gradient of the performance index PI. Practical constraints can be placed upon the allowable regions of the design parameters in a straight forward manner. The optimized design parameters are determined when the performance index PI is minimized A computer program has been implemented in FORTRAN. Examples demonstrate applications of this systematic design technique to small as well as large digital control systems are presented.