scholarly journals Setting a Protective Threshold Value for Silver Towards Freshwater Organisms

2021 ◽  
Author(s):  
Katrien Arijs ◽  
Charlotte Nys ◽  
Patrick Van Sprang ◽  
Karel De Schamphelaere ◽  
Jelle Mertens
Keyword(s):  
Threshold Value ◽  
Freshwater Organisms ◽  
Protective Threshold

In situ irradiation effects studies in medium- and high-voltage TEM

1995 ◽  
Vol 53 ◽  
pp. 234-235
Author(s):  
Charles W. Allen
Keyword(s):  
Cross Section ◽  
Particle Flux ◽  
Threshold Value ◽  
High Energy ◽  
Irradiation Damage ◽  
Defect Complexes ◽  
Lattice Position ◽  
Electrons And Ions ◽  
The Masses

With respect to structural consequences within a material, energetic electrons, above a threshold value of energy characteristic of a particular material, produce vacancy-interstial pairs (Frenkel pairs) by displacement of individual atoms, as illustrated for several materials in Table 1. Ion projectiles produce cascades of Frenkel pairs. Such displacement cascades result from high energy primary knock-on atoms which produce many secondary defects. These defects rearrange to form a variety of defect complexes on the time scale of tens of picoseconds following the primary displacement. A convenient measure of the extent of irradiation damage, both for electrons and ions, is the number of displacements per atom (dpa). 1 dpa means, on average, each atom in the irradiated region of material has been displaced once from its original lattice position. Displacement rate (dpa/s) is proportional to particle flux (cm-2s-1), the proportionality factor being the “displacement cross-section” σD (cm2). The cross-section σD depends mainly on the masses of target and projectile and on the kinetic energy of the projectile particle.

Ein objektanalytisches Verfahren zur Bestimmung der Fläche des nuklidspeichemden Schilddrüsenparenchyms im Szintigramm

1991 ◽  
Vol 30 (01) ◽  
pp. 31-34
Author(s):  
R. Kodym ◽  
R. Seyss
Keyword(s):  
Threshold Value ◽  
Thyroid Uptake

An algorithm for object isolation was developed to determine the area of the thyroid in scintigraphic images, and its volume calculated therefrom so that operator-induced variations, common if the usual manual technique is used, could be avoided. The object isolation is performed for every possible threshold value. The resulting object isolation curves give a reliable and reproducible thyroid area. The method may be used routinely except in cases of blocked thyroid uptake or of multiple autonomous adenomas.

Aktivitätskonzentration der vom Personal einer Radiojodtherapiestation eingeatmeten Luft

1987 ◽  
Vol 26 (03) ◽  
pp. 143-146 ◽  
Author(s):  
H. Fill ◽  
M. Oberladstätter ◽  
J. W. Krzesniak
Keyword(s):  
Nuclear Medicine ◽  
Length Of Stay ◽  
Activity Concentration ◽  
Threshold Value ◽  
Whole Body ◽  
Therapeutic Activity ◽  
External Radiation ◽  
Oral Application ◽  
Exhaled Air ◽  
The Mean

The mean activity concentration of1311 during inhalation by the nuclear medicine personnel was measured at therapeutic activity applications of 22 GBq (600 mCi) per week. The activity concentration reached its maximum in the exhaled air of the patients 2.5 to 4 hours after oral application. The normalized maximum was between 2 • 10−5 and 2 • 10−3 Bq-m−3 per administered Bq. The mean activity concentration of1311 inhaled by the personnel was 28 to 1300 Bq-m−3 (0.8 to 35 nCi-rrf−3). From this the1311 uptake per year was estimated to be 30 to 400 kBq/a (x̄ = 250, SD = 50%). The maximum permitted uptake from air per year is, according to the German and Austrian radiation protection ordinances 22/21 µiCi/a (= 8 • 105 Bq/a). At maximum 50% and, on the average, 30% of this threshold value are reached. The length of stay of the personnel in the patient rooms is already now limited to such an extent that 10% of the maximum permissible whole-body dose for external radiation is not exceeded. Therefore, increased attention should be paid also to radiation exposure by inhalation.

Factors Influencing Leukocyte Adherence in Microvessels

1977 ◽  
Vol 38 (04) ◽  
pp. 0823-0830 ◽  
Author(s):  
Mayrovttz N. Harvey ◽  
Wiedeman P. Mary ◽  
Ronald F. Tuma
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Tissue Injury ◽  
Threshold Value ◽  
In Vivo Studies ◽  
Leukocyte Adherence ◽  
Rolling Velocity ◽  
Subsequent Behavior ◽  
Flow Stasis

SummaryIn vivo studies of the microcirculation of an untraumatized and unanesthetized animal preparation has shown that leukocyte adherence to vascular endothelium is an extremely rare occurrence. Induction of leukocyte adherence can be produced in a variety of ways including direct trauma to the vessels, remote tissue injury via laser irradiation, and denuding the epithelium overlying the observed vessels. The role of blood flow and local hemodynamics on the leukocyte adherence process is quite complex and still not fully understood. From the results reported it may be concluded that blood flow stasis will not produce leukocyte adherence but will augment pre-existing adherence. Studies using 2 quantitative measures of adherence, leukocyte flux and leukocyte velocity have shown these parameters to be affected differently by local hemodynamics. Initial adherence appears to be critically dependent on the magnitude of the blood shear stress at the vessel wall as evidenced by the lack of observable leukocyte flux above some threshold value. Subsequent behavior of the leukocytes as characterized by their average rolling velocity shows no apparent relationship to shear stress but, for low velocities, may be related to the linear blood velocity.

Path Tracking Controller Design of Automatic Guided Vehicle Based on Four-Wheeled Omnidirectional Motion Model

2020 ◽  
Vol 17 (2) ◽  
pp. 7996-8010
Author(s):  
X. Wu ◽  
Y. Yang
Keyword(s):  
Control System ◽  
Fuzzy Controller ◽  
Controller Design ◽  
Threshold Value ◽  
Position Angle ◽  
Path Tracking ◽  
Global Coordinate System ◽  
Automatic Guided Vehicle ◽  
Input Variables ◽  
Industrial Pc

This paper presents a new design of omnidirectional automatic guided vehicle based on a hub motor, and proposes a joint controller for path tracking. The proposed controller includes two parts: a fuzzy controller and a multi-step predictive optimal controller. Firstly, based on various steering conditions, the kinematics model of the whole vehicle and the pose (position, angle) model in the global coordinate system are introduced. Secondly, based on the modeling, the joint controller is designed. Lateral deviation and course deviation are used as the input variables of the control system, and the threshold value is switched according to the value of the input variable to realise the correction of the large range of posture deviation. Finally, the joint controller is implemented by using the industrial PC and the self-developed control system based on the Freescale minimum system. Path tracking experiments were made under the straight and circular paths to test the ability of the joint controller for reducing the pose deviation. The experimental results show that the designed guided vehicle has excellent ability to path tracking, which meets the design goals.

Characterization of Microcrystalline Transition from Amorphous Silicon as a Function of Hydrogen Dilution and Substrate Temperature of Hot-wire CVD

2002 ◽  
Vol 715 ◽  
Author(s):  
Keda Wang ◽  
Haoyue Zhang ◽  
Jian Zhang ◽  
Jessica M. Owens ◽  
Jennifer Weinberg-Wolf ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Sudden Change ◽  
Chemical Vapor ◽  
Threshold Value ◽  
Ir Absorption ◽  
Sudden Increase ◽  
Hot Wire ◽  
Hydrogen Dilution ◽  
Integral Absorption ◽  
Two Peaks

Abstracta-Si:H films were prepared by hot wire chemical vapor deposition. One group was deposited at a substrate temperature of Ts=250°C with varied hydrogen-dilution ratio, 0<R<10; the other group was deposited with fixed R=3 but a varied Ts from 150 to 550°C. IR, Raman and PL spectra were studied. The Raman results indicate that there is a threshold value for the microstructure transition from a- to μc-Si. The threshold is found to be R ≈ 2 at Ts = 250°C and Ts ≈ 200°C at R=3. The IR absorption of Si-H at 640 cm-1 was used to calculate the hydrogen content, CH. CH decreased monotonically when either R or Ts increased. The Si-H stretching mode contains two peaks at 2000 and 2090 cm-1. The ratio of the integral absorption peaks I2090/(I2090+I2090) showed a sudden increase at the threshold of microcrystallinity. At the same threshold, the PL features also indicate a sudden change from a- to μc-Si., i.e. the low energy PL band becomes dominant and the PL total intensity decreases. We attribute the above IR and PL changes to the contribution of microcrystallinity, especially the c-Si gain-boundaries.

Efficient Steganography Algorithm Based On DCT And Entropy Thresholding Technique

2018 ◽  
Vol 8 (1) ◽  
pp. 45
Author(s):  
Satvir Singh
Keyword(s):  
Relative Entropy ◽  
Experimental Work ◽  
Random Function ◽  
Signal To Noise Ratio ◽  
Binary Sequence ◽  
Threshold Value ◽  
Absolute Difference ◽  
Secret Message ◽  
Signal To Noise ◽  
Confidential Information

Steganography is the special art of hidding important and confidential information in appropriate multimedia carrier. It also restrict the detection of  hidden messages. In this paper we proposes steganographic method based on dct and entropy thresholding technique. The steganographic algorithm uses random function in order to select block of the image where the elements of the binary sequence of a secret message will be inserted. Insertion takes place at the lower frequency  AC coefficients of the  block. Before we insert the secret  message. Image under goes dc transformations after insertion of the secret message we apply inverse dc transformations. Secret message will only be inserted into a particular block if  entropy value of that particular block is greater then threshold value of the entropy and if block is selected by the random function. In  Experimental work we calculated the peak signal to noise ratio(PSNR), Absolute difference , Relative entropy. Proposed algorithm give high value of PSNR  and low value of Absolute difference which clearly indicate level of distortion in image due to insertion of secret message is reduced. Also value of  relative entropy is close to zero which clearly indicate proposed algorithm is sufficiently secure. 

Evaluvation of Multiresolution Watermarking Algorithm

2017 ◽  
Vol 7 (8) ◽  
pp. 85
Author(s):  
S. Thabasu Kannan ◽  
S. Azhagu Senthil
Keyword(s):  
Digital Watermarking ◽  
Wavelet Transformation ◽  
Signal To Noise Ratio ◽  
Rapid Development ◽  
Threshold Value ◽  
Discrete Wavelet ◽  
Digital Production ◽  
Common Framework ◽  
Sampling Operation ◽  
Watermarking Scheme

Now-a-days watermarking plays a pivotal role in most of the industries for providing security to their own as well as hired or leased data. This paper its main aim is to study the multiresolution watermarking algorithms and also choosing the effective and efficient one for improving the resistance in data compression. Computational savings from such a multiresolution watermarking framework is obvious. The multiresolutional property makes our watermarking scheme robust to image/video down sampling operation by a power of two in either space or time. There is no common framework for multiresolutional digital watermarking of both images and video. A multiresolution watermarking based on the wavelet transformation is selected in each frequency band of the Discrete Wavelet Transform (DWT) domain and therefore it can resist the destruction of image processing.   The rapid development of Internet introduces a new set of challenging problems regarding security. One of the most significant problems is to prevent unauthorized copying of digital production from distribution. Digital watermarking has provided a powerful way to claim intellectual protection. We proposed an idea for enhancing the robustness of extracted watermarks. Watermark can be treated as a transmitted signal, while the destruction from attackers is regarded as a noisy distortion in channel.  For the implementation, we have used minimum nine coordinate positions. The watermarking algorithms to be taken for this study are Corvi algorithm and Wang algorithm. In all graph, we have plotted X axis as peak signal to noise ratio (PSNR) and y axis as Correlation with original watermark. The threshold value ά is set to 5. The result is smaller than the threshold value then it is feasible, otherwise it is not.

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