The electrodes numbers range from 5 to 64 electrode. Different emotions have been classified such as classification of different four features, which are joy ,relaxation,sadness and fear and the classification of two different features, which are positive and negative emotions. Different stimuli are used in research such as movie clips, and pictures that target different emotions. Different features are extracted, which are Power Spectral Density, Higher Order Spectral, and Common Spatial Pattern. Different temporal windows ranging from 1s to 4s are used with different classifiers such as Support Vector Machine and Linear Discernment Analysis . The accuracy of the different research ranges from 66.51% to 92.5%. This thesis presents a new approach to classify two different classes of emotions which used low cost EEG headset with only one electrode placed on FP1 position according to 10-20 system. Three different types of features were extracted, time domain , power spectrum density , and fractal dimension features. The average accuracy obtained in this thesis is 79.31% to classify two different type of emotions. The solution presented in thesis has accuracy of 79.31% and cost of only $99 which can consider to be a good solution of applications that do not need high percentage of accuracy.The EEG headset used in this thesis was Neurosky Mindwave Mobile which is powered by the Neurosky chip. This headset was a single dry-electrode with only one channel and ground electrode placed on the left ear. This device can be easy to use, raspberry container and can be setup faster compared to other advanced EEG headset.
However, one channel is not enough to detect very complex mental tasks like emotion because different brain lobes are responsible for different functions, and this headset only cover the frontal polar lobe area which is responsible mostly for attention tasks and meditation tasks. Another way to overcome this limitation is to restructure the EEG headset by changing the position of the electrode. For instance, vision activity can be detected better by locating the electrode on the area that contain occipital lobe which is in the back of the skull. Also, positive and negative emotions states have been shown more dominant in the left and right frontal cortices respectively. So, better detection for emotion signal might be achieved by relocating the electrode position to be on the frontal cortices as the desired applications. Another study shows the minimal electrodes can be used to detect the emotion is 4 electrodes located on these positions F3, F4, FP1, FP2 or in these positions O1, O2, P3, P4. So, In order to get a better result the EEG headset can be redesigned to get a better result for detecting vision and emotions activity. Also, increasing the number of the electrodes to 4 can get a better result for detection the emotions.In this thesis, I used LIRIS-ACCEDE library to trigger emotions. Another type of stimulus can be used in order to get better result. There are different systems designed by cognitive psychologist and neuroscientists to trigger emotions. The two systems are International Affective Picture System , and International Affective Digital Sounds . Another database can be used to trigger emotion is Geneva Affective Picture Database. These different system and database can be used to improve our accuracy results in the emotions experiment.
The Mediterranean growing conditions of California’s wine regions, characterized by wet winters and hot dry summers, are predicted to be exacerbated by climate change within this century. These conditions require irrigation to meet target yields and achieve desired grape quality for winemaking. Warming trends since 1880 have caused consistent increases in temperatures in California that are projected to continue through the next century, with the number of hot days predicted to increase by up to three weeks by 2040 . Consequently, climate change has increased the frequency of extreme weather events, with northern coastal regions being the second the most effected by heatwaves in the California . Precipitation in California is projected to increase, on average, but become more variable, rendering vineyard land more vulnerable to drought in dry years, especially in the face of increasing restrictions on using groundwater for irrigation . Vineyard land that relies on snowpack from the Sierras for irrigation will also become more vulnerable to drought, as the snowpack supply for all of the western United States has been projected to diminish by 60% in the next 30 years . Given the likelihood of increasing drought conditions and water restrictions for winegrowers throughout the state, the judicious use of irrigation will become paramount to mitigating impacts on yield and wine quality. One issue affecting ripening grapes in Mediterranean regions that reduces yield, affects berry quality, and has been linked to plant water stress is late-season dehydration . Late-ripening Vitis viniferacultivars, which constituted at least 29% of 2022 California Crush , are especially susceptible to late season dehydration due to changes in climate and winemaking styles .
Harvested as late as October-November, their ripening has traditionally occurred in cooler fall months during which, now, we observe warmer temperatures. Despite evidence that anthropogenic greenhouse gases have pushed forward grape harvests throughout the world, one would be wrong to assume that overall warmer temperatures have caused these grapes to be harvested significantly earlier . Stylistically, there has been a shift in the desired characteristics of wines that necessitates extended hangtime . For example, the average °Brix at harvest for Cabernet Sauvignon in California has increased from 22.0 in 1975 to 25.2, and similar trends exist for total red and white grapes . Such lengthened ripening periods leave grapes more vulnerable to LSD, likely requiring additional irrigation to compensate .The consequences of LSD for winemakers concern the chemical as well as sensory properties of berries and wine. The progression of LSD is strongly correlated to the overall flavor intensity of Syrah grape berries . While that may be a favorable outcome with respect to wine quality, LSD also staggers the development of seed tannin and skin/pulp attributes , two sensory properties winemakers often rely on to gauge overall fruit maturity . Furthermore, for red wine grapes, shriveled berries can cause dramatic shifts in °Brix once in tank, requiring unexpected must treatment and reducing overall predictability of initial conditions for fermentation. In terms of berry chemistry, LSD-stricken berries have lower tartaric and malic acid concentrations, and higher calcium and potassium concentrations, all of which can increase the likelihood of unwanted fungal/bacterial growth during fermentation .In the vineyard, LSD can cause yield losses between 10-30% with the greatest losses occurring in vulnerable cultivars like Syrah . While fruit shrivel of any kind reduces yield, LSD is one of the better understood forms of shrivel in terms of developing prevention strategies compared to the nebulous genetic disorders Bunch Stem Necrosis and Sugar Accumulation Disorder . Sunburn shrivel is commonly solved through shade cloth and cultural practices whereas for LSD, irrigation has been the go-to strategy attempted by growers as well as the main target of research concerning this problem. In quantifying the effects of LSD experimentally, cell vitality, correlated with LSD shrivel in 22 grape cultivars , growing raspberries in container has been measured in berries as a response to varying levels of abiotic stress. Syrah berries were observed to undergo a faster rate of cell death when subjected to either stronger deficit irrigation or elevated temperatures . Likewise, Mendez et al. found that augmenting irrigation at 20 °Brix resulted in a greater berry weight , while also suggesting an even greater need for irrigation in vines with greater crop load to prevent LSD-related loss—another study similarly demonstrates this strategy of ramping up irrigation post veraison resulting in increased berry weight by 13%. Nevertheless, it would be prudent to determine the optimal timing and minimum threshold of post-veraison irrigation for postponing LSD considering the likelihood of increased water restrictions on growers in the future.Our current physiological understanding of berry hydraulics and ripening post-veraison explains why irrigation, and precise irrigation timing, could be critical to reducing late-season dehydration. By the start of veraison, grape berries have completed the first segment of a double sigmoidal growth curve by the end of which cell division is complete and maximum berry size is fixed.
This initial growth is due to the water potential in berry cells dropping as they accumulate solutes thereby drawing in water osmotically and increasing turgor pressure . It is not until veraison where berry elasticity and turgor pressure drop significantly before observed transcriptional changes occur to loosen cell walls for expansion—interestingly, it is not yet accounted for why turgor pressure drops prior to cell wall loosening . Berry turgor pressure continues to decline throughout ripening even as it achieves maximum volume. After veraison, the last phase of berry cell expansion and growth is powered by sap transport into the berry through the phloem. The completion of veraison sees an important shift in the pathway of water transport into grape berries from the xylem to the phloem, reflecting a transition in phloem unloading from a symplastic to an apoplastic pathway that allows sugar to be unloadedinto the berry parenchyma cells against a concentration gradient. A proposed model by Keller et al. suggests that negative xylem water potentials from the canopy down to the berry exert a pulling force on water stored as sap in the parenchyma cells, drawing water through the apoplast into the xylem to be transpired in the canopy. Xylem backflow during ripening has been directly observed by Keller et al. and the relationship between xylem water potential, phloem unloading is evidenced by the observed increase in phloem flow into berries under drought stress . Similar to preparing a sauce reduction from simmering broth, grapevines start with a dilute sap unloaded by the phloem in the berry and leverage evapotranspiration in the canopy to concentrate sugars in the mesocarp. Thus, xylem back flow is a necessary to enable grapevines to reach sugar concentrations suitable for winemaking. Once berries reach maximum size, usually at 24-25 °Brix, phloem transport and skin extensibility decline and further increases in sugar concentrations come from berry dehydration, either through xylem backflow or transpiration through the berry surface, though the latter declines steadily during ripening . Around this time, typically 90-100 days after anthesis depending on the variety, berries begin to lose weight and slowly shrivel. Mesocarp cell death, closely correlated with shrivel , begins near the seeds, eliminating what little turgor pressure is left and accelerating backflow through the xylem . Given that berry water potentials are not negative enough to slow down xylem backflow and phloem inflow is marginal, it is likely too late at this point for irrigation to effectively rehydrate berries. Alternatively, one way grapevines can reduce shrivel is to simply decrease hydraulic conductivity in the pedicel. Chardonnay has been shown to plug up xylem conduits in cane tissue with tyloses, which would reduce backflow and therefore delay LSD, however it remains unclear whether this occurs in the pedicel and if other varieties demonstrate this tendency .There are at least two related metabolic pathways that occur at the onset of ripening that could contribute to the process of mesocarp cell death. For the first pathway, grape berries undergo a significant change in metabolism where malate is catabolized into pyruvate, which increases the respiratory quotient and diminishes the O2 concentration in the berry to the point of hypoxia . Increasingly hypoxic conditions in the center of the mesocarp were correlated with greater cell death in Chardonnay and Syrah, with completely hypoxic conditions occurring at ~100 DAA, within the observed period of cell death in Syrah . This suggests that cultivar differences in onset and rates of cell death are in part due to variation in oxygen availability. Internal O2 concentration is affected by the number of lenticels on the pedicel, which varies between varieties. For example, Xiao et al. found that the total surface area of lenticels on the pedicels was 10-fold larger in Chardonnay than Syrah, which could explain why Chardonnay exhibits slower rates of cell death . This process could also explain why higher nighttime as well as daytime temperatures accelerate cell death, since most berry respiration occurs at night . While seed respiration could to the post veraison respiratory quotient shift. but respiration rates between seeded and seedless varieties do not significantly differ, suggesting that the vast majority of respiration occurs in the mesocarpnot the seeds .