24 research outputs found
Impact of Variable Ordering Cost and Promotional Effort Cost in Deteriorated Economic Order Quantity (EOQ) Model
The instantaneous economic order quantity (EOQ) profit optimization model for deteriorating items is introduced for analyzing the impact of variable ordering cost and promotional effort cost for leveraging profit margins in finite planning horizons. The objective of this model is to maximize the net profit so as to determine the order quantity and promotional effort factor. For any given number of replenishment cycles the existence of a unique optimal replenishment schedule are proved and further the concavity of the net profit function of the inventory system in the number of replenishments is established. The numerical analysis shows that an appropriate policy can benefit the retailer, especially for deteriorating items. Finally, sensitivity analyses with respect to the major parameters are also studied to draw managerial decisions in production systems
A Multilevel Magnetic Synapse Based on Voltage-Tuneable Magnetism by Nitrogen Ion Migration
Altres ajuts: acords transformatius de la UABAltres ajuts: European Union NextGenerationEU/PRTR (grant CNS2022-135230)Advanced synaptic devices with simultaneous memory and processor capabilities are envisaged as core elements of neuromorphic computing (NC) for low-power artificial intelligence. So far, most synaptic devices are based on resistive memories, where the device resistance is tuned with applied voltage or current. However, the use of electric current in such resistive devices causes significant power dissipation due to Joule heating. Higher energy efficiency has been reported in materials exhibiting voltage control of magnetism (VCM). In particular, voltage-driven ion motion to modulate magnetism (magneto-ionics) is an emerging VCM mechanism that can offer new prospects for low-power implementation of NC. In the present work, voltage-driven nitrogen ion motion is exploited in transition metal nitride (CoFeN) thin films (i.e., nitrogen magneto-ionics) to emulate biological synapses. In the proposed device, distinct multilevel non-volatile magnetic states for analog computing and multi-state storage are realized. Moreover, essential synaptic functionalities of the human brain are successfully simulated. The device exhibits an excellent synapse with a remarkable retention time (≈6 months), high switching ratio and large endurance (≈103), for hardware implementation of NC. This research provides new insight into exploiting magneto-ionic-based synaptic devices for spin-based neuromorphic systems
Highly cyclable voltage control of magnetism in cobalt ferrite nanopillars for memory and neuromorphic applications
Tuning the properties of magnetic materials by voltage-driven ion migration (magneto-ionics) gives potential for energy-efficient, non-volatile magnetic memory and neuromorphic computing. Here, we report large changes in the magnetic moment at saturation (mS) and coercivity (HC), of 34% and 78%, respectively, in an array of CoFe2O4 (CFO) epitaxial nanopillar electrodes (∼50 nm diameter, ∼70 nm pitch, and 90 nm in height) with an applied voltage of −10 V in a liquid electrolyte cell. Furthermore, a magneto-ionic response faster than 3 s and endurance >2000 cycles are demonstrated. The response time is faster than for other magneto-ionic films of similar thickness, and cyclability is around two orders of magnitude higher than for other oxygen magneto-ionic systems. Using a range of characterization techniques, magnetic switching is shown to arise from the modulation of oxygen content in the CFO. Also, the highly cyclable, self-assembled nanopillar structures were demonstrated to emulate various synaptic behaviors, exhibiting non-volatile, multilevel magnetic states for analog computing and high-density storage. Overall, CFO nanopillar arrays offer the potential to be used as interconnected synapses for advanced neuromorphic computing applications
Recommended from our members
Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation
Not Available
Not AvailableField experiments were carried out on a sandy loam (Typic -Usochrept) soil in hot dry semi-arid subt tropical climate of Meerut to study the effect of tillage systems and crop residue mulching with fertilizer
Application doze combination on soil physical properties (aggregate size distribution, mean weight diameter (GMD) and bulk density), chemical properties (soil organic carbon (SOC) and soil microbial biomass carbon(MBC)) and it s plant growth parameters and yield continuous wheat (Triticum aestiumL. emend. Fiori
& Paol) system during 2008-11. Two tillage systems and four crop residue mulching
with recommended doze fertilizer (RDF) combination were factorially combined in a split plot design with three replications and each plot size was 5 length and 4 m width. The tillage systems (main plots) were: no tillage (NT) and conventional tillage (CT), i.e. 4 harrowing +1 tine cultivating and one patella. The rice crop residue used as mulching and fertilizer combination treatments (sub-plots) consisted of four M – No mulch + recommended dose of fertilizer
(RDF), M2- Mulch (6 t ha)-1 + recommended dose of fertilizer (120:60:40 kg NPK) (RDF), M -
Mulch (0) + 125% recommended dose of fertilizer (RDF), M - Mulch (6 t ha-1 ) + 125% recommended
dose of fertilizer (RDF). Results revealed that ZT had higher MWDs and lower GMDs than CT at both
depths. The MWDs decreased with increase in soil depth for both tillage (T) treatments as well as rice crop
residue mulching (M) treatments. The bulk density were not affected
significantly (P < 0.05) by tillage 3systems and crop residue mulching × recommended dose of fertilizer
(RDF) application at both 0-15 and 15-30 cm soil depth. Tillage system did not inf luence significantly on
SOC at both depths but MBC influenced significantly (P=0.05) at upper depth (0-15 cm). The SOC and
MBC were affected significantly (P = 0.01) by crop residue mulching with combination of recommended
fertilizer application rate at upper depth (0-15 cm) but 15-30 cm, SOC was significantly at P = 0.05 but
MBC had no significant different. The SOC was significantly higher value in ZT (5.61 g kg -1) than CT(4.69 gkg-1) at 0-15 cm soil depth. The SOC and MBC were recorded in ordered M4>M2>M>M1 which
had significant difference value at P = 0.01.The zero tillage showed significantly (P = 0.01) higher infilt ration
rate (1.96 cm h-1) than conventional tillage. The infiltration rate (IR) was
significantly (P = 0.01) higher in M-1(2.15 cm h-1) followed by M (1.97-cm h-1). Tillage system inf luenced
significantly (P = 0.05) on shoot dry weight and total biomass accumulation
at all three growth stages i.e. ear emergence (EE), BGF and dough stages, however, on LAI at dough
stage, it significant at P = 0.01. The growth parameters (LAI, shoot dry
weight, root dry weight and total biomass accumulation) were influenced significantly (P = 0.01) by
residue mulching with combination of recommended dose of fertilizer (RDF) at beginning grain filling
(BGF) and dough stages, however, at ear emergence stage, it was only significant (P = 0.01) on shoot dry
weight and total biomass accumulation. The higher grain yield value was observed in zero tillage as compared
to conventional tillage. The highest grain yield of wheat cropwas observed in M4 (5.33 t ha-1) and
followed by M2 (5.21 t ha-1), M 3(5.15t ha-1) and M1 (4.62 t ha-1) but difference among the treatments was
non significant.Not Availabl
Emulation of synaptic plasticity on cobalt-based synaptic transistor for neuromorphic computing
Neuromorphic computing (NC), which emulates neural
activities of the human brain, is considered for the low-power implementation
of artificial intelligence. Toward realizing NC, fabrication, and investigations
of hardware elementssuch as synaptic devices and neuronsare crucial.
Electrolyte gating has been widely used for conductance modulation by
massive carrier injections and has proven to be an effective way of emulating
biological synapses. Synaptic devices, in the form of synaptic transistors, have
been studied using various materials. Despite the remarkable progress, the
study of metallic channel-based synaptic transistors remains massively
unexplored. Here, we demonstrated a three-terminal electrolyte gatingmodulated
synaptic transistor based on a metallic cobalt thin film to emulate biological synapses. We have realized gating-controlled,
non-volatile, and distinct multilevel conductance states in the proposed device. The essential synaptic functions demonstrating both
short-term and long-term plasticity have been emulated in the synaptic device. A transition from short-term to long-term memory
has been realized by tuning the gate pulse parameters, such as amplitude and duration. The crucial cognitive behavior, including
learning, forgetting, and re-learning, has been emulated, showing a resemblance to the human brain. Beyond that, dynamic filtering
behavior has been experimentally implemented in the synaptic device. These results provide an insight into the design of metallic
channel-based synaptic transistors for NC.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)National Research Foundation (NRF)Submitted/Accepted versionThe authors acknowledge the support from the CRP grant NRF-CRP21-2018-003 of the National Research Foundation (NRF), Singapore. S.N.P. acknowledges the partial support from the Tier 2 grant MOE2019-T2-1-117 of the Ministry of Education (MOE) Singapore. P.M. thanks the Ministry of Education (MoE), India, and the Pratiksha Trust for the financial support. X.R.W. acknowledges support from the Agency for Science, Technology and Research (A*STAR) under its AME IRG grant (project no. A20E5c0094)
Synaptic plasticity investigation in permalloy based channel material for neuromorphic computing
Artificial synaptic devices capable of synchronized storing and processing of information are the critical building blocks of neuromorphic computing systems for the low-power implementation of artificial intelligence. Compared to the diverse synaptic device structures, the emerging electrolyte-gated synaptic transistors are promising for mimicking biological synapses owing to their analogous working mode. Despite the remarkable progress in electrolyte-gated synaptic transistors, the study of metallic channel-based synaptic devices remains vastly unexplored. Here, we report a three-terminal electrolyte-gated artificial synapse based on metallic permalloy as the active layer. Gating controlled, non-volatile, rewritable, and distinct multilevel conductance states have been achieved for analog computing. Representative synaptic behaviors such as excitatory postsynaptic conductance (EPSC), paired-pulse facilitation (PPF), spike amplitude-dependent plasticity (SADP), spike duration-dependent plasticity (SDDP), and long-term potentiation/depression (LTP/D) have been successfully simulated in the synaptic device. Furthermore, switching from short-term to long-term memory regimes has been demonstrated through repeated training. Benefitting from the short-term facilitation, the synaptic device can also act as a high-pass temporal filter for selective communication. This research highlights the great potential of metallic channel-based synaptic devices for future neuromorphic systems and augments the diversity of synaptic devices.Ministry of Education (MOE)National Research Foundation (NRF)Submitted/Accepted versionThe authors acknowledge the support from the CRP Grant NRF-CRP21-2018-0003 of the National Research Foundation (NRF), Singapore. SNP acknowledges the partial support from the Tier 2 grant MOE2019-T2-1-117 of the Ministry of Education (MOE) Singapore. PSAK acknowledges support from the Ministry of Education (MoE), India
A multilevel electrolyte-gated artificial synapse based on ruthenium-doped cobalt ferrite
Synaptic devices that emulate synchronized memory and processing are considered the core components of neuromorphic computing systems for the low-power implementation of artificial intelligence. In this regard, electrolyte-gated transistors (EGTs) have gained much scientific attention, having a similar working mechanism as the biological synapses. Moreover, compared to a traditional solid-state gate dielectric, the liquid dielectric has the key advantage of inducing extremely large modulation of carrier density while overcoming the problem of electric pinholes, that typically occurs when using large-area films gated through ultra-thin solid dielectrics. Herein we demonstrate a three-terminal synaptic transistor based on ruthenium-doped cobalt ferrite (CRFO) thin films by electrolyte gating. In the CRFO-based EGT, we have obtained multilevel non-volatile conductance states for analog computing and high-density storage. Furthermore, the proposed synaptic transistor exhibited essential synaptic behavior, including spike amplitude-dependent plasticity (SADP), spike duration-dependent plasticity (SDDP), long-term potentiation (LTP), and long-term depression (LTD) successfully by applying electrical pulses. This study can motivate the development of advanced neuromorphic devices that leverage simultaneous modulation of electrical and magnetic properties in the same device and show a new direction to synaptic electronics.Ministry of Education (MOE)National Research Foundation (NRF)Submitted/Accepted versionThe authors acknowledge the support from the CRP grant NRF-CRP21-2018-0003 of the National Research Foundation (NRF), Singapore. SNP acknowledges the partial support from the Tier 2 Grant MOE2019-T2-1-117 of the Ministry of Education (MOE) Singapore. PSAK acknowledges support from the Ministry of Education (MoE), India
Synaptic behavior of Fe₃O₄-based artificial synapse by electrolyte gating for neuromorphic computing
Neuromorphic computing (NC) is a crucial step toward realizing power-efficient artificial intelligence systems. Hardware implementation of NC is expected to overcome the challenges associated with the conventional von Neumann computer architecture. Synaptic devices that can emulate the rich functionalities of biological synapses are emerging. Out of several approaches, electrolyte-gated synaptic transistors have attracted enormous scientific interest owing to their similar working mechanism. Here, we report a three-terminal electrolyte-gated synaptic transistor based on Fe3O4 thin films, a half-metallic spinel ferrite. We have realized gate-controllable multilevel, non-volatile, and rewritable states for analog computing. Furthermore, we have emulated essential synaptic functions by applying electrical stimulus to the gate terminal of the synaptic device. This work provides a new candidate and a platform for spinel ferrite-based devices for future NC applications.Ministry of Education (MOE)National Research Foundation (NRF)Submitted/Accepted versionThe authors acknowledge the support from the CRP Grant No. NRF-CRP21-2018-0003 of the National Research Foundation (NRF), Singapore. S.N.P. acknowledges the partial support from the Tier 2 Grant No. MOE2019-T2-1-117 of the Ministry of Education (MOE) Singapore. P.M. thanks the Ministry of Education (MoE), India, and the Pratiksha Trust, India, for the financial support. S.G.B. acknowledges INSPIRE Faculty Fellowship, DST, INDIA for the funding