Perturbation of the sierpinski antenna to allocate the operating bands

A scheme for modifying the spacing between the bands of the Sierpinski antenna is introduced. Experimental results of two novel designs of fractal antennas suggest that the fractal structure can be perturbed to enable the log-period to be changed while still maintaining the multiband behaviour of the antenna.Peer ReviewedPostprint (published version

Small but long koch fractal monopole

A small but long wire fractal antenna based on the Koch curve is presented. Experimental and numerical results show that the antenna improves the features of a common linear monopole. The radiation resistance is increased and the Q is reduced at each fractal iteration, approaching the fundamental limit on small antennas.Peer ReviewedPostprint (published version

Decomposition of diacetone alcohol in packed beds of ion exchange resins

A study was made of the rate of decomposition of diacetone alcohol by anion exchange resins in a packed bed under adiabatic and isothermal conditions. Two different resins were compared: a conventional type gel structure resin, Amberlite IRA-400, and a newly marketed maorore-ticular resin, Amberlyst A-26. In a substrate with low water content, the rate of decomposition of diacetone alcohol by Amberlite IRA-400 vas controlled by intraparticle diffusion. This vas due to shrinkage of the polymer chain matrix of the resin. When dry diacetone alcohol feed was introduced the amount of decomposition was not measurable. It was found that the macroreticular type resin, Amberlyst A-26 was considerably more effective as a catalyst due to its porous structure. Decreasing the water content of the feed actually increased the rate of decomposition. Amberlyst A-26 effectively catalyzed the decomposition of dry diacetone alcohol. Intraparticle diffusion does not control the rate of decomposition over the range of variables studied. The equilibrium concentration at 25°C for this reaction,using the Amberlyst resin, was determined by extrapolating to zero space velocity the concentration of acetone in the effluent. The value obtained was 88.95 weight per cent acetone. This is in reasonable agreement with the value reported by Davis and Burrows (6) of 88.27%, who conducted the decomposition reaction at 25°C in an agitated batch system using barium hydroxide as a catalytic agent. A value of the equilibrium constant of K = 18.65 was calculated from the Amberlyst equilibrium concentration data at 25°C. An attempt was made to develop a mathematical model for the flow reaction in a packed bed, using the simplifying assumption that a single step controlled the overall rate. Equations have been derived for the following cases: First order kinetic control unidirectional. Bidirectional first order kinetic control. Bidirectional reaction, first order for the decomposition and second order for the formation of diacetone alcohol. Film diffusion control. Intraparticle diffusion control. It was found that none of the above reaction mechanisms involving diffusion and reaction kinetics could be reduced to a linear or non linear form and solved with the data obtained using Amberlyst A-26 at 25°C over the entire range of variable studied. Therefore, the simplifying assumption that a single step controls the overall rate does not seem to apply for the system studied. The effect of film diffusion vas studied by varying the superficial velocity while maintaining all other variables constant. The differences in superficial velocity did not affect the conversions obtained using Amberlyst A-26. It was concluded that film diffusion to and from the bulk of the fluid did not influence the rate of decomposition of diacetone alcohol for superficial velocities in the range of 0.001 to 0.014 feet per second. This study, as veil as the entire investigation, was conducted in the laminar flow region of low Reynolds Numbers. The first order kinetic equation for the unidirection reaction will fit the experimental data for conversions below 85W. Above 85% conversion, the effect of the reverse reaction becomes apparent. The rate constant for the decomposition of diacetone alcohol by Amberlyst A-26 resin at 25°C was calculated and found to be k = 0.0194 sec.-1 which compares favorably with a value of k = 0.0205 sec.-1 reported by Akerlof (1) using 0.1N KOH for first order kinetics at the same temperature of 25°C. Basinski and Narebeka (2) reported a value of k a 0.000535 sec.-1 for the decomposition reaction at 25°C using Amberlite IRA-400 in a batch system with an ethanol-water substrate

On real-time partitioned multicore systems

Partitioning is a common approach to developing mixed-criticality systems, where partitions are isolated from each other both in the temporal and the spatial domain in order to prevent low-criticality subsystems from compromising other subsystems with high level of criticality in case of misbehaviour. The advent of many-core processors, on the other hand, opens the way to highly parallel systems in which all partitions can be allocated to dedicated processor cores. This trend will simplify processor scheduling, although other issues such as mutual interference in the temporal domain may arise as a consequence of memory and device sharing. The paper describes an architecture for multi-core partitioned systems including critical subsystems built with the Ada Ravenscar profile. Some implementation issues are discussed, and experience on implementing the ORK kernel on the XtratuM partitioning hypervisor is presented

Memory isolation in many-core embedded systems

The current approach to developing mixed-criticality sys- tems is by partitioning the hardware resources (processors, memory and I/O devices) among the different applications. Partitions are isolated from each other both in the temporal and the spatial domain, so that low-criticality applications cannot compromise other applications with a higher level of criticality in case of misbehaviour. New architectures based on many-core processors open the way to highly parallel systems in which each partition can be allocated to a set of dedicated proces- sor cores, thus simplifying partition scheduling and temporal separation. Moreover, spatial isolation can also benefit from many-core architectures, by using simpler hardware mechanisms to protect the address spaces of different applications. This paper describes an architecture for many- core embedded partitioned systems, together with some implementation advice for spatial isolation

Challenges for the colombian central government in post-agreement financing

El presente artículo de investigación analiza las dificultades en el aumento de ingresos del gobierno central en un entorno de post-acuerdo. A través de un análisis de componentes principales y hechos estilizados se encuentra que no existen suficientes recursos monetarios disponibles para ejecutar el acuerdo de paz. Esto puede resultar en una implementación incompleta de los acuerdos que implique una revisión del gasto público en educación, sistema pensional, sistema sanitario, economía rural, servicio de deuda, infraestructuras de transporte y el fortalecimiento de la DIAN para incrementar y redistribuir la carga tributaria.This paper analyzes the difficulties in raising tax revenue for the central government in a post-agreement era. Through an analysis of main components and stylized facts it is found that there are not enough monetary resources available to implement the peace agreement. This may result inan incomplete implementation of the agreement and a revision of public spending in education, pension system, health system, rural economy, debt service, transport infrastructure and strengthening the DIAN to increase and redistribute the tax burden

13. Integrating information on the role of mosquitoes for the transmission of pathogens of wildlife

Traditionally, mosquitoes have been studied given their relevance as vectors of pathogens that affect humans. However, in recent decades, their relevance as vectors of pathogens that affect wildlife has become evident. For this reason, multidisciplinary research disciplines have been developed focusing on the ecology, epidemiology and evolution of the interactions between pathogens and their hosts, including the transmission dynamics of diseases. However, there is a gap in the knowledge of mosquito-borne pathogens that affect wildlife, being necessary to study the taxa diversity, using genomic tools and, of course, their life cycles and their vectors. However, the information on the vector competence of mosquitoes for the transmission of pathogens that affect wild animals is certainly scarce. Interspecific and intraspecific differences have been evidenced. This would determine the capacity of mosquitoes to transmit parasites that infect wild animals. Different factors such as physiological and biochemical processes, or the mosquito microbiota could determine these differential capacities of mosquitoes to transmit pathogens.RGL was partially supported by a Margalida Comas contract from the Government of the Balearic Islands co-financed by the European Regional Development Fund (FEDER) (REF: PD/038/2019) and a Juan de la Cierva Formación contract (REF: FJC2019-041291-I). JMP was financed by the project PID2020-118205GB-I00 from the Spanish Ministry of Science and Innovation co-financed by the European Regional Development Fund (FEDER)

Genetic colour polymorphism is associated with avian malarial infections

Peer reviewe