Solving the potential field local minimum problem using internal agent states

We propose a new, extended artificial potential field method, which uses dynamic internal agent states. The internal states are modelled as a dynamical system of coupled first order differential equations that manipulate the potential field in which the agent is situated. The internal state dynamics are forced by the interaction of the agent with the external environment. Local equilibria in the potential field are then manipulated by the internal states and transformed from stable equilibria to unstable equilibria, allowiong escape from local minima in the potential field. This new methodology successfully solves reactive path planning problems, such as a complex maze with multiple local minima, which cannot be solved using conventional static potential fields

Swarm robot social potential fields with internal agent dynamics

Swarm robotics is a new and promising approach to the design and control of multiagent robotic systems. In this paper we use a model for a second order non-linear system of self-propelled agents interacting via pair-wise attractive and repulsive potentials. We propose a new potential field method using dynamic agent internal states to successfully solve a reactive path-planning problem. The path planning problem cannot be solved using static potential fields due to local minima formation, but can be solved by allowing the agent internal states to manipulate the potential field. Simulation results demonstrate the ability of a single agent to perform reactive problem solving effectively, as well as the ability of a swarm of agents to perform problem solving using the collective behaviour of the entire swarm

Wall following to escape local minima for swarms of agents using internal states and emergent behaviour

Natural examples of emergent behaviour, in groups due to interactions among the group's individuals, are numerous. Our aim, in this paper, is to use complex emergent behaviour among agents that interact via pair-wise attractive and repulsive potentials, to solve the local minima problem in the artificial potential based navigation method. We present a modified potential field based path planning algorithm, which uses agent internal states and swarm emergent behaviour to enhance group performance. The algorithm is used successfully to solve a reactive path-planning problem that cannot be solved using conventional static potential fields due to local minima formation. Simulation results demonstrate the ability of a swarm of agents to perform problem solving using the dynamic internal states of the agents along with emergent behaviour of the entire group

A Broadband UHF Tag Antenna For Near-Field and Far-Field RFID Communications

The paper deals with the design of passive broadband tag antenna for Ultra-High Frequency (UHF) band. The antenna is intended for both near and far fields Radio Frequency Identification (RFID) applications. The meander dipole tag antenna geometry modification is designed for frequency bandwidth increasing. The measured bandwidth of the proposed broadband Tag antenna is more than 140 MHz (820–960 MHz), which can cover the entire UHF RFID band. A comparison between chip impedance of datasheet and the measured chip impedance has been used in our simulations. The proposed progressive meandered antenna structure, with an overall size of 77 mm × 14 mm × 0.787 mm, produces strong and uniform magnetic field distribution in the near-field zone. The antenna impedance is matched to common UHF chips in market simply by tuning its capacitive and inductive values since a perfect matching is required in the antenna design in order to enhance the near and the far field communications. Measurements confirm that the designed antenna exhibits good performance of Tag identification for both near-field and far-field UHF RFID applications

Homogenization of a capillary phenomena

We study the height of a liquid in a tube when it contains a great number of thin vertical bars and when its border is finely strained. For this, one uses an epi-convergence method

Molecular characterization of two microalgal strains in Egypt and investigation of the antimicrobial activity of their extracts

The emergence of new pathogens and the increasing drug-resistance of recognized ones pose a difficult challenge. One way that this challenge is being addressed is through the discovery of new cost-effective drug resources in the form of bioactive compounds. Algae represent a promising source of bioactive compounds in this regard. In the present research, we used molecular and phylogenetic analysis to isolate and identify two microalgal strains. We found that one strain belonged to the phylum chrysophyta and the other to the cyanobacteria. We also investigated the antimicrobial activity of some of the lipophilic extracts of the two microalgal strains. Several fractions showed high individual antimicrobial bioactivity against multidrug-resistant Salmonella sp., Citrobacter sp., Aspergillus niger and Aspergillus flavus. Fraction III from Poterioochromonas malhamensis showed the highest level of activity against two multidrug-resistant bacterial pathogens. The inhibition zone diameter was 1.4 cm for Salmonella and 1.4 cm for Citrobacter. Meanwhile, another lipophilic fraction from the cyanobacterium Synechocystis salina showed broad-spectrum bioactivity (inhibition zone diameter of 0.9 cm for Aspergillus niger, 1 cm for Citrobacter and 0.9 cm for Salmonella). One lipophilic fraction from Aphanizomenon showed antifungal bioactivity against Aspergillus niger and Aspergillus flavus, where the inhibition zone diameter was 1.1 cm and 1.0 cm, respectively. The study highlights the antimicrobial bioactivity of extracts from local microalgae and emphasizes the importance of carrying out screening programs for those microorganisms

On the AA-spectrum for AA-bounded operator on von-Neumann algebra

Let $\mathfrak{M}$ be a von Neumann algebra and let $A$ be a nonzero positive element of $\mathfrak{M}$. By $\sigma_A(T)$ and $r_A(T)$ we denote the $A$-spectrum and the $A$-spectral radius of $T\in\mathfrak{M}^A$, respectively. In this paper, we show that $\sigma(PTP, P\mathfrak{M} P)\subseteq \sigma_A(T)$. Sufficient conditions for the equality $\sigma_A(T)=\sigma(PTP, P\mathfrak{M} P)$ to be true are presented. Also, we show that $\sigma_A(T)$ is finite for any $T\in\mathfrak{M}^A$ if and only if $A$ is in the socle of $\mathfrak{M}$. Next , we consider the relationship between elements $S$ and $T\in\mathfrak{M}^A$ that satisfy one of the following two conditions: (1) $\sigma_A(SX)=\sigma_A(TX)$ for all $X\in\mathfrak{M}^A$, (2) $r_A(SX)= r_A(TX)$ for all $X\in\mathfrak{M}^A$. Finally, a Gleason-Kahane-\.Zelazko's theorem for the $A$-spectrum is derived.% Finally, we introduce and study the notion of the $A$-approximate point spectrum for element of $X\in\mathfrak{M}^A$

Aphrodisiac effect of aqueous stem bark extract ofFicus sycomorus on female wistar rats

In the present study, the effect of aqueous stem bark extract of Ficus sycomorus was evaluated on female sex hormones and sexual behavior in female Wistar rats. Adult female rats having regular estrous cycle confirmed by daily cytology of the vaginal smear analysis were used. Rats were  randomly divided into 3 groups (n=10): Group I served as a control; while group II, and III received 40 mg/kg and 80 mg/kg of the extracts  respectively. The results revealed significant increase (p<0.5) in serum concentration of the estradiol in group II and a significant decrease (p<0.5) in serum concentration of estradiol in group III in comparison with the control. There was also significant decrease (p<0.5) in serum level of progesterone in group II and no significant effect in group III in comparison with the control. The result also indicated no significant effect (p>0.5) of the extract on female sexual behavior, which may suggest no scientific basis for the use of the extract as an aphrodisiac in females.Keywords: Ficus sycomorus, Aphrodisiac, Estradiol, Progesterone, Lordosis quotien