XClusters: Explainability-first Clustering

We study the problem of explainability-first clustering where explainability becomes a first-class citizen for clustering. Previous clustering approaches use decision trees for explanation, but only after the clustering is completed. In contrast, our approach is to perform clustering and decision tree training holistically where the decision tree's performance and size also influence the clustering results. We assume the attributes for clustering and explaining are distinct, although this is not necessary. We observe that our problem is a monotonic optimization where the objective function is a difference of monotonic functions. We then propose an efficient branch-and-bound algorithm for finding the best parameters that lead to a balance of cluster distortion and decision tree explainability. Our experiments show that our method can improve the explainability of any clustering that fits in our framework.Comment: 11 page

Sink-oriented Dynamic Location Service Protocol for Mobile Sinks with an Energy Efficient Grid-Based Approach

Sensor nodes transmit the sensed information to the sink through wireless sensor networks (WSNs). They have limited power, computational capacities and memory. Portable wireless devices are increasing in popularity. Mechanisms that allow information to be efficiently obtained through mobile WSNs are of significant interest. However, a mobile sink introduces many challenges to data dissemination in large WSNs. For example, it is important to efficiently identify the locations of mobile sinks and disseminate information from multi-source nodes to the multi-mobile sinks. In particular, a stationary dissemination path may no longer be effective in mobile sink applications, due to sink mobility. In this paper, we propose a Sink-oriented Dynamic Location Service (SDLS) approach to handle sink mobility. In SDLS, we propose an Eight-Direction Anchor (EDA) system that acts as a location service server. EDA prevents intensive energy consumption at the border sensor nodes and thus provides energy balancing to all the sensor nodes. Then we propose a Location-based Shortest Relay (LSR) that efficiently forwards (or relays) data from a source node to a sink with minimal delay path. Our results demonstrate that SDLS not only provides an efficient and scalable location service, but also reduces the average data communication overhead in scenarios with multiple and moving sinks and sources

Improvement of Growth and Morphology of Vegetable Seedlings with Supplemental Far-Red Enriched LED Lights in a Plant Factory

Although light-emitting diode (LED) lamps have been broadly applied in horticultural production to improve plant yield and quality, compared to natural light there is a disadvantage in the lack of far-red light in the LED spectrum. Far-red light has been studied widely to control plant growth and development. Therefore, this study aimed to find the effect of supplemental far-red-enriched LED lights to control the growth of tomato, red pepper, cucumber, gourd, watermelon and bottle gourd seedlings. The treatments were cool white LED:far-red LED at ratios of 5:0, 5:1, 5:2 and 5:3. The growth of tomato and red pepper seedlings, including hypocotyl length, was correlated to far-red light and light intensity. The phytochrome photostationary state (PSS) value of maximum hypocotyl length by supplemental far-red-enriched light ranged from 0.69 to 0.77 in tomato and red pepper seedlings. Although hypocotyl lengths of cucumber and watermelon were greatly affected by PSS, the PSS value for maximum hypocotyl length was lower than for tomato and red pepper. These results show that manipulating supplemental far-red enrichment can be used to control vegetable seedling growth with some variation among plant species

Improvement of Growth and Morphology of Vegetable Seedlings with Supplemental Far-Red Enriched LED Lights in a Plant Factory

Although light-emitting diode (LED) lamps have been broadly applied in horticultural production to improve plant yield and quality, compared to natural light there is a disadvantage in the lack of far-red light in the LED spectrum. Far-red light has been studied widely to control plant growth and development. Therefore, this study aimed to find the effect of supplemental far-red-enriched LED lights to control the growth of tomato, red pepper, cucumber, gourd, watermelon and bottle gourd seedlings. The treatments were cool white LED:far-red LED at ratios of 5:0, 5:1, 5:2 and 5:3. The growth of tomato and red pepper seedlings, including hypocotyl length, was correlated to far-red light and light intensity. The phytochrome photostationary state (PSS) value of maximum hypocotyl length by supplemental far-red-enriched light ranged from 0.69 to 0.77 in tomato and red pepper seedlings. Although hypocotyl lengths of cucumber and watermelon were greatly affected by PSS, the PSS value for maximum hypocotyl length was lower than for tomato and red pepper. These results show that manipulating supplemental far-red enrichment can be used to control vegetable seedling growth with some variation among plant species.Y

Growth and quality of sprouts of six vegetables cultivated under different light intensity and quality

Vegetable sprouts (alfalfa, broccoli, clover, kohlrabi, radish, and red radish) were cultivated under three monochromatic light regimes (red, green, and blue) with five different light intensities (0, 12.5, 25, 50, and 100 µmol·m-2·s-1) to investigate the effects of light intensity and quality on the growth and total phenolic content of the vegetable sprouts. The light quality and intensity had a direct effect on hypocotyl elongation in vegetable sprouts. Increasing blue light intensity enhanced suppression of hypocotyl elongation in all of the vegetable sprouts. Red light also reduced hypocotyl length in alfalfa and clover sprouts comparing those grown in darkness. The fresh weight of broccoli and radish sprouts markedly increased when red light intensity was 100 µmol·m-2·s-1; however, light use efficiency (LUE) decreased with increasing light intensity. Total phenolic content was reduced by increasing red light intensity in alfalfa and red radish sprouts.OAIID:oai:osos.snu.ac.kr:snu2015-01/102/0000027607/4ADJUST_YN:YEMP_ID:A075898DEPT_CD:517CITE_RATE:.725FILENAME:2015-08-heb-새싹_광질_광량-곽유리나_김경구.pdfDEPT_NM:식물생산과학부SCOPUS_YN:YCONFIRM:

Flower development and fruit malformation in strawberries after short-term exposure to high or low temperature

Strawberry plants are at risk of exposure to short-term high daytime temperature (HTD) during flowering and exposure to short-term low temperature at night (LTN) during the coldest months of winter. The aim of this study was to identify the effects of short-term HTD or LTN on the different floral developments and fruit development, such as fruit malformation, flowering traits, stigma maturation, and pollen quality in 'Seolhyang' and 'Maehyang' strawberries. For the treatment of HTD, plants were treated at 35 degrees C, and for LTN treatment, plants were treated at 2 degrees C for consecutive days each. Days to flowering were shortened under HTD in both cultivars, while days to anther dehiscence were shortened under HTD. Stigma maturation was delayed by short-term extreme temperature stress in 'Maehyang'. Short-term LTN before the flower petals appeared in the first and second flower clusters might cause high malformation rates in both cultivars. Pollen viability and the germination rate were decreased by HTD and LTN in both cultivars. There was a high correlation between the lower pollen germination rate and the higher percentage of malformed fruits under short-term LTN. These results suggest that even shortterm exposure to low temperature in winter during cultivation should be controlled carefully considering developmental stages and cultivar-specific responses and that attention should be paid to the protection of strawberries.N

The combined conditions of photoperiod, light intensity, and air temperature control the growth and development of tomato and red pepper seedlings in a closed transplant production system

Understanding environmental factors is essential to maximizing the biomass production of plants. There have been many studies on the effects of the photosynthetic photon flux (PPF), photoperiod and air temperature as separate factors affecting plants, including under a closed transplant production system (CTPS). However, few studies have investigated the combined effects of these factors on plant growth. Germinated tomato and red pepper seedlings were transferred to three different photoperiods with five different photosynthetic photon fluxes (PPFs) at an air temperature of 25/20 degrees C to investigate plant growth under a different daily light integral (DLI). Three different air temperatures, 23/20, 25/20, and 27/20 degrees C (photo/dark periods), with five different PPFs were used to examine plant growth under different DIFs (difference between the day and night temperature). Increasing the DLI from 4.32 to 21.60 mol center dot m(-2)center dot d(-1), either by increasing the photoperiod or PPF, improved the growth of seedlings in both cultivars. However, when comparing treatments that provided the same DLI, tomato seedlings had s significantly higher growth when grown under longer photoperiods and s lower PPF. Even in higher DLI conditions, reduced growth due to higher PPF indicated that excessive light energy was a limiting factor. At 23 and 25 degrees C, tomato seedlings showed similar correlation curves between growth and PPF. However, at the higher temperature of 27 degrees C, while the slope of the curve at low PPFs was similar to that of the curves at lower temperatures, the slope at high PPFs was flatter. On the other hand, red pepper seedlings displayed the same correlation curve between growth and PPF at all tested temperatures, and red pepper plants accumulated more dry weight even at higher temperatures. These results suggested that the combination effect was more useful to observe these overall tendencies, especially in reacting to a second factor. This will provide us with more information and a deeper understanding of plant characteristics and how they will behave under changing environments.Y

Effect of the light spectrum of white LEDs on the productivity of strawberry transplants in a plant factory with artificial lighting

The application of plant factory with artificial lighting (PFAL) for producing strawberry transplants (S-PFAL) was recently introduced due to the capacity for high quality and year-round transplant production. To achieve greater efficiency with this system, it is essential to select lighting sources that have a suitable spectrum for runner plant propagation. This study was conducted to investigate the effects of the light spectrum of white light-emitting diodes (LEDs), which have a different correlated color temperature compared with that of white fluorescent lamps, on the growth of strawberry (Fragaria x ananassa Duch. cv. Maehyang) propagules and runner plants in a PFAL. Uniform propagules with one fixed runner each were placed into a PFAL for transplant production and were grown under either warm-white LEDs (WWL), mint-white LEDs (MWL), or cool-white fluorescent lamps (CWF) for 21 days. The propagules in the MWL treatment group had the greatest number of leaves, leaf area, top/root dry weight ratio and number of newly formed runners per propagule among the treatments. The dry weight of the newly formed runners of each propagule was also greatest after MWL treatment, whereas it was lowest after CWF treatment. However, there was no significant difference in the growth parameters of the runner plants among the three treatments. The photosynthetic photon efficacy of WWL and MWL was 5.40 mu mol s(- 1) W- 1, which was 62.6% higher than that of CWF (3.38 mu mol s(- 1) W- 1). The dry weight efficacies of the MWL, WWL, and CWF treatments were 23.5, 22.1, and 10.0 g kWh(- 1), respectively. These results indicate that MWL with high photosynthetic photon efficacy can have positive effects on the runner formation and growth of strawberry propagules and can replace cool-white fluorescent lamps in an S-PFAL.N

Growth and physiological responses of Panax ginseng seedlings as affected by light intensity and photoperiod

The effects of light intensity and photoperiod, and their combination as daily light integrals (DLI) on the growth and physiological traits of Panax ginseng seedlings were investigated to establish a light environment for seedling production. Stratified seeds of Panax ginseng 'Chunpoong' were sown. The seedlings were cultivated for 20 weeks using warm-white LEDs with DLI from 1.44 to 10.94 mol m(-2) d(-1), which are combinations of three light intensities (50, 120, and 190 mu mol m(-2) s(-1)) and three photoperiods (8, 12, and 16 h d(-1)) in a plant factory with artificial lighting (PFAL). As the DLI increased, the shoot length and leaf area were exponentially reduced after shoot development at both nine and 20 weeks of treatments. At nine weeks of treatment, the greater light intensity and longer photoperiod treatments, where the shoot established fastest, the photosynthetic products were translocated to the roots first and the dry weight distribution in the root increased as DLI increased. In the high light intensity and long photoperiod treatments, SPAD value, maximum (F-v/F-m), and minimum (F-v/F-o) quantum efficiency tended to decrease, and the photosynthetic traits were negatively affected over time with leaf senescence. The root growth rate in high light intensity with long photoperiod treatments seemed to lag behind that in low light intensity with short photoperiod treatments. As a result, this study found that a light intensity of 50 mu mol m(-2) s(-1) with a 12 h d(-1) photoperiod (DLI of 2.16 mol m(-2) d(-1)) was a suitable light environment for both shoot and root growth of ginseng seedlings. Further, the shoot establishment should be considered to design a light environment for ginseng seedling production in a PFAL.N