positive zero
Recently Published Documents


TOTAL DOCUMENTS

112
(FIVE YEARS 26)

H-INDEX

14
(FIVE YEARS 3)

Entropy ◽  
2022 ◽  
Vol 24 (1) ◽  
pp. 99
Author(s):  
Eduard Jorswieck ◽  
Pin-Hsun Lin ◽  
Karl-Ludwig Besser

It is known that for a slow fading Gaussian wiretap channel without channel state information at the transmitter and with statistically independent fading channels, the outage probability of any given target secrecy rate is non-zero, in general. This implies that the so-called zero-outage secrecy capacity (ZOSC) is zero and we cannot transmit at any positive data rate reliably and confidentially. When the fading legitimate and eavesdropper channels are statistically dependent, this conclusion changes significantly. Our work shows that there exist dependency structures for which positive zero-outage secrecy rates (ZOSR) are achievable. In this paper, we are interested in the characterization of these dependency structures and we study the system parameters in terms of the number of observations at legitimate receiver and eavesdropper as well as average channel gains for which positive ZOSR are achieved. First, we consider the setting that there are two paths from the transmitter to the legitimate receiver and one path to the eavesdropper. We show that by introducing a proper dependence structure among the fading gains of the three paths, we can achieve a zero secrecy outage probability (SOP) for some positive secrecy rate. In this way, we can achieve a non-zero ZOSR. We conjecture that the proposed dependency structure achieves maximum ZOSR. To better understand the underlying dependence structure, we further consider the case where the channel gains are from finite alphabets and systematically and globally solve the ZOSC. In addition, we apply the rearrangement algorithm to solve the ZOSR for continuous channel gains. The results indicate that the legitimate link must have an advantage in terms of the number of antennas and average channel gains to obtain positive ZOSR. The results motivate further studies into the optimal dependency structures.


2021 ◽  
Vol 10 (2) ◽  
pp. 114-125
Author(s):  
Pavel Potužák

The theory of interest of Irving Fisher was designed to explain positive, zero, and negative interest rate. One of the intertemporal equilibria with the zero interest is an economy with a given supply of hardtacks for shipwrecked sailors. Hardtacks can be fully saved for the future, but their stock cannot be enlarged by production. Fisher presented several streams of consumption of hardtacks over time. This paper shows that the Fisherian paths are not consistent with the dynamic optimization model. Different trajectories of the optimum consumption are calculated and sketched. Their shape depends on the value of the subjective discount rate, the intertemporal elasticity of substitution in consumption, and the lifetime horizon of the shipwrecked sailors. None of them resemble the original Fisher examples.


2021 ◽  
Author(s):  
W. N. Adyani W. Razak ◽  
Nor Idah Kechut ◽  
Edward Andrews ◽  
Samuel Krevor

Abstract Spatial image resolution has limited previous attempts to characterize the thin film flow of oil sandwiched in-between gas and water in a three-phase fluid system This paper describes how a systematically designed displacement experiment can produce imagery to define the film flow process in a 3D pore space of water-wet sandstone rocks. We image multiphase flow at the pore scale through three displacement experiments conducted on water-wet outcrop rock with variable spreading tendencies. The experiment has been formulated to observe the relationship between fluid spreading, phase saturations, and pore-scale displacement mechanisms. We provide exhaustive evidence of the three-phase fluid configurations that serve as a proxy mechanism assisting the fluid displacement process in a three-phase system, which includes the oil sandwiches in-between water and gas, the flow of oil via clay fabrics, and the double-displacement process that generates oil and water film in 3D pore spaces. Further, we show evidence that the stable thin-oil film has enhanced the gas trapping mechanism in the water-wet rocks. We observed that the oil layer had covered the isolated and trapped gas blobs, enhancing their stability. As a result, the trapped gas in the positive and zero spreading systems is slightly higher than in the negative spreading system due to a stable oil film. We analyze the Euler characteristic of the individual fluid phases and the interface pair of the fluids during waterflooding, gas injection, and chase water flooding. The comparison of the Euler characteristic for the connected and disconnected fluid phases between three different spreading systems (i.e., positive, zero, and negative) shows that the oil layer's connectivity is highest in the positive spreading system and lowest in the negative spreading system. The oil layer in the positive spreading system is also thicker than in the negative spreading system.


Circuit World ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alireza Goudarzian

Purpose Control-signal-to-output-voltage transfer function of the conventional boost converter has at least one right-half plane zero (RHPZ) in the continuous conduction mode which can restrict the open-loop bandwidth of the converter. This problem can complicate the control design for the load voltage regulation and conversely, impact on the stability of the closed-loop system. To remove this positive zero and improve the dynamic performance, this paper aims to suggest a novel boost topology with a step-up voltage gain by developing the circuit diagram of a conventional boost converter. Design/methodology/approach Using a transformer, two different pathways are provided for a classical boost circuit. Hence, the effect of the RHPZ can be easily canceled and the voltage gain can be enhanced which provides conditions for achieving a smaller working duty cycle and reducing the voltage stress of the power switch. Using this technique makes it possible to achieve a good dynamic response compared to the classical boost converter. Findings The observations show that the phase margin of the proposed boost converter can be adequately improved, its bandwidth is largely increased, due to its minimum-phase structure through RHPZ cancellation. It is suitable for fast dynamic response applications such as micro-inverters and fuel cells. Originality/value The introduced method is analytically studied via determining the state-space model and necessary criteria are obtained to achieve a minimum-phase structure. Practical observations of a constructed prototype for the voltage conversion from 24 V to 100 V and various load conditions are shown.


Author(s):  
Soodeh Zarepour

In this paper, we study a new class of holographic heat engines via charged AdS black hole solutions of Einstein gravity coupled with logarithmic nonlinear [Formula: see text] gauge theory. So, logarithmic [Formula: see text] AdS black holes with a horizon of positive, zero and negative constant curvatures are considered as a working substance of a holographic heat engine and the corrections to the usual Maxwell field are controlled by nonlinearity parameter [Formula: see text]. The efficiency of an ideal cycle ([Formula: see text]), consisting of a sequence of isobaric [Formula: see text] isochoric [Formula: see text] isobaric [Formula: see text] isochoric processes, is computed using the exact efficiency formula. It is shown that [Formula: see text], with [Formula: see text] the Carnot efficiency (the maximum efficiency available between two fixed temperatures), decreases as we move from the strong coupling regime ([Formula: see text]) to the weak coupling domain ([Formula: see text]). We also obtain analytic relations for the efficiency in the weak and strong coupling regimes in both low and high temperature limits. The efficiency for planar and hyperbolic logarithmic [Formula: see text] AdS black holes is computed and it is observed that efficiency versus [Formula: see text] behaves in the same qualitative manner as the spherical black holes.


2021 ◽  
Vol 13 (16) ◽  
pp. 9326
Author(s):  
Samer Ali Al-shami ◽  
Abdullah Al Mamun ◽  
Nurulizwa Rashid ◽  
Mohammed Al-shami

Microcredit financing is extensively considered as an effective development method for poverty mitigation and women empowerment. Nevertheless, relevant studies reflected opposing outcomes on microfinance effects consisting of positive, zero, and negative impacts. Thus, this research investigated Al-Amal Bank’s microcredit impacts on women empowerment in Yemen, one of the poorest Middle Eastern nations. A panel dataset and primary and secondary data were gathered through household surveys and propensity score matching to restrict intangible variables’ possible effects. The empirical results revealed that microcredit had a significant positive effect on monthly household incomes and accumulated asset values. Although microcredit facilitated female entrepreneurship and income generation for improved household incomes and expenditure, no influence was found on female household decisions and mobility following the patriarchal system practised in many Arabian nations, including Yemen. Hence, the study finding has theoretically and practically contributed to the body of knowledge in three ways. First, a novel proof of how microcredit interactions affected several Yemeni women empowerment elements was identified. This study also provides new insight into the empowerment theory by explaining how access to microcredit influences numerous features of women’s economic and social empowerment. Lastly, social and family traditions significantly influenced female attributes and lifestyles by reflecting how communal and family rituals affected microcredit impacts on women empowerment and vice versa. Conversely, this study guides Yemeni policymakers and those from other nations on extending financial services for self-development to reduce poverty and drive women empowerment rather than relying on government and international agencies.


Author(s):  
Adam K. Spector ◽  
Annabelle M Mournet ◽  
Deborah J Snyder ◽  
Emmanuella Eastman ◽  
Maryland Pao ◽  
...  

Background: Despite prevention efforts, suicide rates continue to rise, prompting the need for novel evidence-based approaches to suicide prevention. Patients presenting with foot and ankle disorders in a podiatric medical and surgical practice may represent a population at risk for suicide, given risk factors of chronic pain and debilitating injury. Screening has the potential to identify people at risk that may otherwise go unrecognized. This quality improvement project (QIP) aimed to determine the feasibility of implementing suicide risk screening in an outpatient podiatry clinic and ambulatory surgical center. Methods: A suicide risk screening QIP was implemented in an outpatient podiatry clinic and ambulatory surgical center in collaboration with a National Institute of Mental Health (NIMH) suicide prevention research team. Following training for all staff, patients ages 18 years and older were screened for suicide risk with the Ask Suicide-Screening Questions (ASQ) as standard of care. Clinic staff were surveyed about their opinions of screening. Results: Ninety-four percent of patients (442/470) agreed to be screened for suicide risk and nine patients (2%; 9/442) screened non-acute positive; zero for acute risk. The majority of clinic staff reported that they found screening acceptable, felt comfortable working with patients who have suicidal thoughts, and thought screening for suicide risk was clinically useful. Conclusions: Suicide risk screening was successfully implemented in an outpatient podiatry clinic. Screening with the ASQ provided valuable information that would not have been ascertained otherwise, positively impacting clinical decision-making and leading to improved overall care for podiatry patients.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mulaine Shih ◽  
Jiashi Miao ◽  
Michael Mills ◽  
Maryam Ghazisaeidi

AbstractWe revisit the meaning of stacking fault energy (SFE) and the assumptions of equilibrium dissociation of lattice dislocations in concentrated alloys. SFE is a unique value in pure metals. However, in alloys beyond the dilute limit, SFE has a distribution of values depending on the local atomic environment. Conventionally, the equilibrium distance between partial dislocations is determined by a balance between the repulsive elastic interaction between the partial dislocations and a unique value for SFE. This assumption is used to determine SFE from experimental measurements of dislocation splitting distances in metals and alloys, often contradicting computational predictions. We use atomistic simulations in a model NiCo alloy to study the dislocation dissociation process in a range of compositions with positive, zero, and negative average SFE and surprisingly observe a stable, finite splitting distance in all cases at low temperatures. We then compute the decorrelation stress and examine the balance of forces on the partial dislocations, considering the local effects on SFE, and observe that even the upper bound of SFE distribution alone cannot satisfy the force balance in some cases. Furthermore, we show that in concentrated solid solutions, the resisting force caused by interaction of dislocations with the local solute environment becomes a major force acting on partial dislocations. Here, we show that the presence of a high solute/dislocation interaction, which is not easy to measure and neglected in experimental measurements of SFE, renders the experimental values of SFE unreliable.


Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 972
Author(s):  
Modjtaba Ghorbani ◽  
Matthias Dehmer

The definition of orbit polynomial is based on the size of orbits of a graph which is OG(x)=∑ix|Oi|, where O1,…,Ok are all orbits of graph G. It is a well-known fact that according to Descartes’ rule of signs, the new polynomial 1−OG(x) has a positive root in (0,1), which is unique and it is a relevant measure of the symmetry of a graph. In the current work, several bounds for the unique and positive zero of modified orbit polynomial 1−OG(x) are investigated. Besides, the relation between the unique positive root of OG in terms of the structure of G is presented.


Author(s):  
Ousmane Z Traoré ◽  
Lota D Tamini

Abstract This article theoretically and empirically disentangles the effects of maximum residue limits (MRLs) for pesticides on production, export supply and import demand. We adopt a modelling approach based on the costs and benefits associated with food safety standards and use our theoretical framework to assess the empirical net effects of MRLs for pesticides on African mango production and trade with Organisation for Economic Co-operation and Development (OECD) member countries. On the one hand, we theoretically highlight that for a given production technology and a level of elasticity of production costs with respect to the MRL gap, producers will likely (probability and quantity) produce standard-compliant products if they are able to completely pass through the standard-compliance costs to the unit price they receive from exporters; otherwise, they will exit standard-compliant products market. On the other hand, we theoretically show that the net effects of the MRL gap on bilateral trade can be positive, zero or negative depending on the effects of consumers’ perceived quality (positive), trade costs (negative) and standard-compliant production cost (negative). We use a cross-sectional data set for 12 African countries that produced and exported MRL-compliant mangoes to 31 OECD countries in 2016. On the one hand, we find that the net effect of MRLs is positive for the level of standard-compliant mango production and negative for the probability of producing. On the other hand, they are positive in mango trade between African and OECD member countries. Our results highlight that the tightening or imposition of strict MRLs for pesticides in developed countries may be trade promoting, while they severely impede production in African countries.


Sign in / Sign up

Export Citation Format

Share Document