scholarly journals An Electromagnetic Analysis of Noise-Based Intrinsically Secure Communication in Wireless Systems

Electronics ◽  
2018 ◽  
Vol 7 (7) ◽  
pp. 113 ◽  
Author(s):  
Marco Migliore ◽  
Daniele Pinchera ◽  
Mario Lucido ◽  
Fulvio Schettino ◽  
Gaetano Panariello
Keyword(s):  
Mutual Information ◽  
Secure Communication ◽  
Communication Systems ◽  
Degrees Of Freedom ◽  
Antenna Design ◽  
Artificial Noise ◽  
Electromagnetic Propagation ◽  
Interesting Approach ◽  
The Difference

Recently there has been an increasing interest toward unconditionally secure communication systems in which the mechanism assuring the secrecy of the message is physical and not computational. An interesting approach proposed in the information theory literature for unconditionally secure communication is based on the use of artificial noise at a rate related to the difference between the mutual information in perfect secrecy. Since the mechanism assuring the secrecy of the message is physical and not computational, the unauthorized receiver cannot obtain information from the received signal, regardless of how much computational power is available. For this reason, such a cryptographic system is called unconditionally secure. The aim of this paper is to investigate an electromagnetic approach to the noise-based wireless communication systems stressing the important role of the electromagnetic propagation and antenna design. In particular, the concept of the number of degrees of freedom of the field is used to clarify the physical mechanism that allows for a decrease in the mutual information of the unauthorized channel compared to the eavesdropper channel. Numerical examples regarding both free-space propagation and rich scattering environments are shown, confirming the importance of the role of the electromagnetic propagation and antenna design.

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

Open and Secure Communication - EDI is not enough

2013 ◽  
Author(s):  
Thomas Abdallah ◽  
Ralph Holbein ◽  
Patrick Scheidegger ◽  
Dr. Stephanie Teufel
Keyword(s):  
Information Exchange ◽  
Secure Communication ◽  
Communication Systems ◽  
Production Factor ◽  
Information Industry ◽  
Structured Information ◽  
The Difference ◽  
Information Interchange ◽  
Market Pressures ◽  
Open Office

From the 1994 CAIS Conference:The Information Industry in TransitionMcGill University, Montreal, Quebec. May 25 - 27, 1994.Information is becoming an important production factor. Businesses are being forced to communicate and exchange information with each other because of market pressures such as increased competition, the internationalization of markets, and specialization of production processes. To survive, businesses must streamline both in-house and external communications while at the same time ensuring the quality, timeliness, and availability of information. Information Technology (IT), in the form of open office communication systems, provides a means for supporting this exchange of information. These systems provide a means for hardware- and software-independent communications within the organization as well as communication between organizations. Organizations depend on both the availability of information and the use of IT system. Together called as the electronic information interchange. Since information is primarily represented in the form of documents, open office communication relies on the use of document standards. This paper examines document standards focusing on the difference between loosely and highly structured information exchange and also the role of security which is an important issue for organizations depending on open eletronic information exchange.

scholarly journals Information in the Nonstationary Case

2009 ◽  
Vol 21 (3) ◽  
pp. 688-703 ◽  
Author(s):  
Vincent Q. Vu ◽  
Bin Yu ◽  
Robert E. Kass
Keyword(s):  
Mutual Information ◽  
Conditional Distribution ◽  
Direct Method ◽  
Conditional Entropy ◽  
Difficult Problem ◽  
Response Distribution ◽  
Direct Estimate ◽  
Estimation Strategy ◽  
The Difference

Information estimates such as the direct method of Strong, Koberle, de Ruyter van Steveninck, and Bialek (1998) sidestep the difficult problem of estimating the joint distribution of response and stimulus by instead estimating the difference between the marginal and conditional entropies of the response. While this is an effective estimation strategy, it tempts the practitioner to ignore the role of the stimulus and the meaning of mutual information. We show here that as the number of trials increases indefinitely, the direct (or plug-in) estimate of marginal entropy converges (with probability 1) to the entropy of the time-averaged conditional distribution of the response, and the direct estimate of the conditional entropy converges to the time-averaged entropy of the conditional distribution of the response. Under joint stationarity and ergodicity of the response and stimulus, the difference of these quantities converges to the mutual information. When the stimulus is deterministic or nonstationary the direct estimate of information no longer estimates mutual information, which is no longer meaningful, but it remains a measure of variability of the response distribution across time.

scholarly journals Antenna design and fabrication for biotelemetry applications

2021 ◽  
Vol 11 (4) ◽  
pp. 3639
Author(s):  
Sourav Sinha ◽  
Raja Rashidul Hasan ◽  
Ta-Seen Reaz Niloy ◽  
Md. Abdur Rahman
Keyword(s):  
Human Body ◽  
Patch Antenna ◽  
Communication Systems ◽  
Open Space ◽  
Research Work ◽  
Antenna Design ◽  
Total Efficiency ◽  
Phantom Model ◽  
Copper Material

<span>This research work assumes the role of designing a Micro-strip patch antenna that exists with in the band range of 402 MHz to 405 MHz, which was considered as medical implantable communication systems (MICS) band and can be possibly implanted at human body phantom model because of its flexiblility and lower radiation characteristics. CST Microwave studio was used for designing the patch antenna and the human body phantom model with the existence of homogeneous layers (fat, skin and muscle) and the final version was fabricated. Being highly flexible, FR4 was chosen as a substrate to maintain 0.5 mm thickness throughout. For the ground and patch, copper material was selected having thickness of 0.018 mm. For the ease of fabrication and biocompatibility, silicon was selected with the thickness of being 8 mm. Maximum specific absorption rate of the proposed antenna was obtained 0.588 W/Kg for 10g tissue. Various Parameters such as VSWR, S11, Radiation efficiency, Total efficiency were found 1.1889, -21.28 dB, <br /> -45.71 dB, -45.74 dB respectively inside body phantom that ensure the antenna design was efficiently and effectively suitable for biotelemetry system which is body implantable. After fabrication the value of S11 is found -12.43 dB in open space with 453 MHz frequency.</span>

scholarly journals On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

The role of differential phase contrast in electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 176-177
Author(s):  
E.M. Waddell ◽  
J.N. Chapman ◽  
R.P. Ferrier
Keyword(s):  
Phase Contrast ◽  
Practical Method ◽  
Position Vector ◽  
Differential Phase ◽  
Pure Phase ◽  
Differential Phase Contrast ◽  
The Difference ◽  
Image Position ◽  
First Moment

Dekkers and de Lang (1977) have discussed a practical method of realising differential phase contrast in a STEM. The method involves taking the difference signal from two semi-circular detectors placed symmetrically about the optic axis and subtending the same angle (2α) at the specimen as that of the cone of illumination. Such a system, or an obvious generalisation of it, namely a quadrant detector, has the characteristic of responding to the gradient of the phase of the specimen transmittance. In this paper we shall compare the performance of this type of system with that of a first moment detector (Waddell et al.1977).For a first moment detector the response function R(k) is of the form R(k) = ck where c is a constant, k is a position vector in the detector plane and the vector nature of R(k)indicates that two signals are produced. This type of system would produce an image signal given bywhere the specimen transmittance is given by a (r) exp (iϕ (r), r is a position vector in object space, ro the position of the probe, ⊛ represents a convolution integral and it has been assumed that we have a coherent probe, with a complex disturbance of the form b(r-ro) exp (iζ (r-ro)). Thus the image signal for a pure phase object imaged in a STEM using a first moment detector is b2 ⊛ ▽ø. Note that this puts no restrictions on the magnitude of the variation of the phase function, but does assume an infinite detector.

On the Role of Transferrin in 67Ga Uptake by Tumor Cells

1988 ◽  
Vol 27 (04) ◽  
pp. 151-153
Author(s):  
P. Thouvenot ◽  
F. Brunotte ◽  
J. Robert ◽  
L. J. Anghileri
Keyword(s):  
Specific Binding ◽  
Subcellular Fractionation ◽  
Animal Blood ◽  
Tumor Bearing ◽  
Cell Structures ◽  
The Difference ◽  
Sarcoma Cells ◽  
In Vitro Uptake

In vitro uptake of 67Ga-citrate and 59Fe-citrate by DS sarcoma cells in the presence of tumor-bearing animal blood plasma showed a dramatic inhibition of both 67Ga and 59Fe uptakes: about ii/io of 67Ga and 1/5o of the 59Fe are taken up by the cells. Subcellular fractionation appears to indicate no specific binding to cell structures, and the difference of binding seems to be related to the transferrin chelation and transmembrane transport differences

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