Moran considered a dam whose inflow in a given interval of time is a continuous random variable. He then developed integral equations for the probabilities of emptiness and overflow. These equations are difficult to s...Moran considered a dam whose inflow in a given interval of time is a continuous random variable. He then developed integral equations for the probabilities of emptiness and overflow. These equations are difficult to solve numerically;thus, approximations have been proposed that discretize the input. In this paper, extensions are considered for storage systems with different assumptions for storage losses. We also develop discrete approximations for the probabilities of emptiness and overflow.展开更多
Post-harvest storage losses (PHLs) remain significant in Sub-Saharan Africa (SSA) due to several factors mainly insect pests and molds. Hermetic storage technologies (HSTs) are being promoted to address these storage ...Post-harvest storage losses (PHLs) remain significant in Sub-Saharan Africa (SSA) due to several factors mainly insect pests and molds. Hermetic storage technologies (HSTs) are being promoted to address these storage losses. In Uganda, HSTs were first introduced in 2012. However, its use among farming households remains low today. Data were collected from 306 smallholder farmers from four districts of Northern Uganda using a pre-tested semi-structured questionnaire to understand their knowledge, use, and constraints to the adoption of hermetic storage. A multivariate Logit regression model was used to find the significance of the factors affecting adoption. Results showed low awareness and use of hermetic storage among smallholder farmers. Only 53.3% of the interviewed farmers were aware of the use of hermetic storage for grain storage. The SuperGrain bag was the most known form of hermetic storage (35.3%), followed by the Purdue Improved Crop Storage (PICS) bag (34.9%), metallic silo (15.5%), and plastic silo (14.4%). Hermetic storage use was even lower as only 17.6% of the surveyed farmers were using one or more forms of hermetic storage to store their grains. Insect pest management without chemical insecticides was the main reason (83.1%) for hermetic storage use. About 75.5% of those aware of hermetic storage had received training in the technology. Hermetic storage use in farming households led to improved food availability, household income, and nutrition. Lack of local availability (50.2%), high costs (37.8%), and inadequate knowledge (6.9%) were the main constraints hindering the adoption of hermetic storage in Northern Uganda. The logit regression models showed that only training in hermetic storage significantly (p = 0.002) affected farmers’ decision to adopt hermetic storage. Understanding the factors that constrain the adoption of HSTs could provide policymakers with important information to initiate and design policies and programs aimed at reducing crop storage losses.展开更多
We show that absorbed and stored electromagnetic energy are proportional to the reflection group delay in highly reflective dispersive dielectric mirrors over the high-reflectivity band. Our theoretical considerations...We show that absorbed and stored electromagnetic energy are proportional to the reflection group delay in highly reflective dispersive dielectric mirrors over the high-reflectivity band. Our theoretical considerations are verified by numerical simulations performed on different dielectric mirror structures. The revealed pro- portionality between group delay and absorbed energy sets constraint on the application of ultrabroadband and/or dispersive dielectric mirrors in broadband or widely tunable, high-power laser systems.展开更多
Polymeric dielectrics have wide range of applications in the field of electrical energy storage because of their light weight and easy processing. However, the state-of-the-art polymer dielectrics, such as biaxially o...Polymeric dielectrics have wide range of applications in the field of electrical energy storage because of their light weight and easy processing. However, the state-of-the-art polymer dielectrics, such as biaxially orientated polypropylene, could not meet the demand of minimization of electronic devices because of its low energy density. Recently, poly（vinylidene fluoride） （PVDF） based ferroelectric polymers have attracted considerable interests for energy storage applications because of their high permittivity and high breakdown strength. Unfortunately, the high dielectric loss and/or high remnant polarization of PVDF-based polymers seriously limits their practical applications for electrical energy storage. Since the discovery of relaxor ferroelectric behavior was firstly reported in irradiated poly（vinylidene fluoride- trifluoroethylene） （P（VDF-TrFE）） copolyrner, many strategies have been developed to enhanced the electrical energy storage capability, including copolymerization, grafting, blending and fabricating of multilayer How these methods affect the polymorphs, crystallinity, crystal size of PVDF-based polymers and the connection between these microstructures and their corresponding energy storage properties are discussed in detail.展开更多
文摘Moran considered a dam whose inflow in a given interval of time is a continuous random variable. He then developed integral equations for the probabilities of emptiness and overflow. These equations are difficult to solve numerically;thus, approximations have been proposed that discretize the input. In this paper, extensions are considered for storage systems with different assumptions for storage losses. We also develop discrete approximations for the probabilities of emptiness and overflow.
文摘Post-harvest storage losses (PHLs) remain significant in Sub-Saharan Africa (SSA) due to several factors mainly insect pests and molds. Hermetic storage technologies (HSTs) are being promoted to address these storage losses. In Uganda, HSTs were first introduced in 2012. However, its use among farming households remains low today. Data were collected from 306 smallholder farmers from four districts of Northern Uganda using a pre-tested semi-structured questionnaire to understand their knowledge, use, and constraints to the adoption of hermetic storage. A multivariate Logit regression model was used to find the significance of the factors affecting adoption. Results showed low awareness and use of hermetic storage among smallholder farmers. Only 53.3% of the interviewed farmers were aware of the use of hermetic storage for grain storage. The SuperGrain bag was the most known form of hermetic storage (35.3%), followed by the Purdue Improved Crop Storage (PICS) bag (34.9%), metallic silo (15.5%), and plastic silo (14.4%). Hermetic storage use was even lower as only 17.6% of the surveyed farmers were using one or more forms of hermetic storage to store their grains. Insect pest management without chemical insecticides was the main reason (83.1%) for hermetic storage use. About 75.5% of those aware of hermetic storage had received training in the technology. Hermetic storage use in farming households led to improved food availability, household income, and nutrition. Lack of local availability (50.2%), high costs (37.8%), and inadequate knowledge (6.9%) were the main constraints hindering the adoption of hermetic storage in Northern Uganda. The logit regression models showed that only training in hermetic storage significantly (p = 0.002) affected farmers’ decision to adopt hermetic storage. Understanding the factors that constrain the adoption of HSTs could provide policymakers with important information to initiate and design policies and programs aimed at reducing crop storage losses.
基金supported by the National Development Agency of Hungary in the ELI hELIOS preparatory project under Grant No. ELI-09-1-2010-0010
文摘We show that absorbed and stored electromagnetic energy are proportional to the reflection group delay in highly reflective dispersive dielectric mirrors over the high-reflectivity band. Our theoretical considerations are verified by numerical simulations performed on different dielectric mirror structures. The revealed pro- portionality between group delay and absorbed energy sets constraint on the application of ultrabroadband and/or dispersive dielectric mirrors in broadband or widely tunable, high-power laser systems.
基金support from Special Fund of the National Priority Basic Research of China (No. 2014CB239503)the National Natural Science Foundation of China (Nos. 51522703, 51477096) was acknowledged
文摘Polymeric dielectrics have wide range of applications in the field of electrical energy storage because of their light weight and easy processing. However, the state-of-the-art polymer dielectrics, such as biaxially orientated polypropylene, could not meet the demand of minimization of electronic devices because of its low energy density. Recently, poly（vinylidene fluoride） （PVDF） based ferroelectric polymers have attracted considerable interests for energy storage applications because of their high permittivity and high breakdown strength. Unfortunately, the high dielectric loss and/or high remnant polarization of PVDF-based polymers seriously limits their practical applications for electrical energy storage. Since the discovery of relaxor ferroelectric behavior was firstly reported in irradiated poly（vinylidene fluoride- trifluoroethylene） （P（VDF-TrFE）） copolyrner, many strategies have been developed to enhanced the electrical energy storage capability, including copolymerization, grafting, blending and fabricating of multilayer How these methods affect the polymorphs, crystallinity, crystal size of PVDF-based polymers and the connection between these microstructures and their corresponding energy storage properties are discussed in detail.
