An EHF resonant tunnel diode oscillator

1996 ◽  
Vol 74 (S1) ◽  
pp. 243-247
Author(s):  
M. Roschke ◽  
C. Chan ◽  
O. Berolo
Keyword(s):  
Quantum Wells ◽  
Mbe Growth ◽  
Resonant Tunnelling ◽  
Long Term Stability ◽  
Wafer Probing ◽  
Device Applications ◽  
Resonant Tunnel ◽  
High Degree ◽  
Tunnel Diode Oscillator

Resonant tunnelling diodes (RTDs) are emerging as some of the more promising electron devices in the field of communications. The rapid progress of molecular beam epitaxy (MBE) growth techniques during the last decade has resulted in RTDs that exhibit remarkable peak-to-valley ratios, opening the door to a variety of useful device applications. To study the applicability of low-power EHF oscillators for personal communications and global-positioning system applications, we fabricated RTDs using AlAs/GaAs/AlAs double- barrier quantum wells and a MESFET fabrication process. The dc and rf characteristics of the RTDs, which showed a high degree of bistability, were obtained by on-wafer probing using an HP8510 network analyzer with a cascade probe station. The devices were then used in a number of simple hybrid oscillator circuits on alumina substrates. Focusing on the oscillation frequency of 37 GHz, we report on the room-temperature short-, medium-, and long-term stability of the oscillators while monitoring thermal drift and dc bias control.

scholarly journals Ion Selective Amperometric Biosensors for Environmental Analysis of Nitrate, Nitrite and Sulfate

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4326
Author(s):  
Niels Peter Revsbech ◽  
Michael Nielsen ◽  
Deby Fapyane
Keyword(s):  
Inorganic Ions ◽  
Natural Environments ◽  
Nitrogen Transformations ◽  
Redox Transformation ◽  
Whole Cells ◽  
Long Term Stability ◽  
High Degree ◽  
Insight Into ◽  
A Current

Inorganic ions that can be redox-transformed by living cells can be sensed by biosensors, where the redox transformation gives rise to a current in a measuring circuit. Such biosensors may be based on enzymes, or they may be based on application of whole cells. In this review focus will be on biosensors for the environmentally important ions NO3−, NO2−, and SO42−, and for comparison alternative sensor-based detection will also be mentioned. The developed biosensors are generally characterized by a high degree of specificity, but unfortunately also by relatively short lifetimes. There are several investigations where biosensor measurement of NO3− and NO2− have given new insight into the functioning of nitrogen transformations in man-made and natural environments such as sediments and biofilms, but the biosensors have not become routine tools. Future modifications resulting in better long-term stability may enable such general use.

Polyaniline/nano-in2O3 Composites Used as a Sensitive Material to NH3

2011 ◽  
Vol 239-242 ◽  
pp. 322-327 ◽  
Author(s):  
Ying Nan Xie ◽  
Zheng Hai Shi ◽  
Jian Lian Liu
Keyword(s):  
In Situ Polymerization ◽  
Average Diameter ◽  
Environmental Stability ◽  
Sensitive Material ◽  
Long Term Stability ◽  
Degree Of Crystallization ◽  
High Degree ◽  
Sulphosalicylic Acid

In presence of nano-In2O3 which were synthesised via a reverse microemulsion, Polyaniline/nano-In2O3 composites were prepared by in-situ polymerization of aniline in 5-sulphosalicylic acid(SSA) aqueous solution. They were characterized by means of TEM, XRD and FTIR.. TEM and XRD showed that the average diameter of In2O3 particles was 15nm with a narrow size distribution and with a high degree of crystallization. The FTIR suggested that the structure of PAn-SSA was not be changed by the mixture of In2O3. Sensitivity of the composites to 100~1000ppm NH3 were studied, the results reveal that polyaniline/nano-In2O3 composites have short response time and good reversibility, the gas sensitive of composites to NH3 under 300ppm increased linearly with the increasing concentration of NH3 and decreased with the increasing of In2O3 concentration. Long-term stability of polyaniline/nano-In2O3 composites were also investagated, it can be concluded that the organic-inorganic hybrid materials have better environmental stability.

MBE growth of InAs/AlInAs strained-layer multi quantum wells for optical device applications

1989 ◽  
Vol 95 (1-4) ◽  
pp. 210-214 ◽  
Author(s):  
Yuichi Matsushima ◽  
Hiroshi Kato ◽  
Katsuyuki Utaka ◽  
Kazuo Sakai
Keyword(s):  
Quantum Wells ◽  
Mbe Growth ◽  
Optical Device ◽  
Strained Layer ◽  
Device Applications

scholarly journals Accuracy and Long-Term Stability Assessment of Inductive Conductivity Cell Measurements on Argo Floats

2020 ◽  
Vol 37 (12) ◽  
pp. 2209-2223
Author(s):  
Nikolay P. Nezlin ◽  
Mathieu Dever ◽  
Mark Halverson ◽  
Jean-Michel Leconte ◽  
Guillaume Maze ◽  
...  
Keyword(s):  
Statistical Tool ◽  
Argo Floats ◽  
Term Stability ◽  
Long Term Stability ◽  
Sensor Package ◽  
New Sensors ◽  
High Degree ◽  
The Western Pacific ◽  
Conductivity Cell

AbstractThis study demonstrates the long-term stability of salinity measurements from Argo floats equipped with inductive conductivity cells, which have extended float lifetimes as compared to electrode-type cells. New Argo float sensor payloads must meet the demands of the Argo governance committees before they are implemented globally. Currently, the use of CTDs with inductive cells designed and manufactured by RBR, Ltd., has been approved as a Global Argo Pilot. One requirement for new sensors is to demonstrate stable measurements over the lifetime of a float. To demonstrate this, data from four Argo floats in the western Pacific Ocean equipped with the RBRargo CTD sensor package are analyzed using the same Owens–Wong–Cabanes (OWC) method and reference datasets as the Argo delayed-mode quality control (DMQC) operators. When run with default settings against the standard DMQC Argo and CTD databases, the OWC analysis reveals no drift in any of the four RBRargo datasets and, in one case, an offset exceeding the Argo target salinity limits. Being a statistical tool, the OWC method cannot strictly determine whether deviations in salinity measurements with respect to a reference hydrographic product (e.g., climatologies) are caused by oceanographic variability or sensor problems. So, this study furthermore investigates anomalous salinity measurements observed when compared with a reference product and demonstrates that anomalous values tend to occur in regions with a high degree of variability and can be better explained by imperfect reference data rather than sensor drift. This study concludes that the RBR inductive cell is a viable option for salinity measurements as part of the Argo program.

A ZOOGEOGRAPHIC ANALYSIS OF THE NOCTUIDAE (LEPIDOPTERA) OF BERINGIA, AND SOME INFERENCES ABOUT PAST BERINGIAN HABITATS

1988 ◽  
Vol 120 (S144) ◽  
pp. 109-123 ◽  
Author(s):  
J.D. Lafontaine ◽  
D.M. Wood
Keyword(s):  
Habitat Preferences ◽  
Source Area ◽  
The Arctic ◽  
Long Term Stability ◽  
Abundant Evidence ◽  
Central Canada ◽  
Northwestern North America ◽  
High Degree ◽  
Limited Exchange

AbstractThe 245 species of Noctuidae known from Beringia, i.e. northwestern North America and northeastern Asia, are arranged in six groups based on their habitat preferences. These groups are analysed in terms of their distribution, endemism within Beringia, and zoogeographic affinities. The fauna associated with taiga, boreomontane forests and southern steppe (prairie) habitats shows only limited evidence of continuous occurrence in Beringia, and limited exchange during the Pleistocene between the Nearctic and Palaearctic. We have concluded therefore that this fauna has entered the Beringian area in Recent times following deglaciation of western and central Canada. In wet and dry tundra habitats, in contrast, there is abundant evidence of trans-Beringian faunal exchange. A high degree of endemism in dry tundra habitats within Beringia today is evidence of long-term stability of this habitat. These patterns, as well as evidence from a limited fossil sample of mid-Wisconsinan age, allow us to speculate on Beringian habitats during Wisconsinan times. We further conclude that the eastern Palaearctic and Beringia was the source area for the fauna that repopulated the Canadian Arctic after deglaciation. By contrast, non-Beringian refugia of the Nearctic have contributed little to the fauna of the Arctic.

Stability and Change in Emotional Intelligence: Exploring the Transition to Young Adulthood

2005 ◽  
Vol 26 (2) ◽  
pp. 100-106 ◽  
Author(s):  
James D.A. Parker ◽  
Donald H. Saklofske ◽  
Laura M. Wood ◽  
Jennifer M. Eastabrook ◽  
Robyn N. Taylor
Keyword(s):  
High School ◽  
Emotional Intelligence ◽  
Postsecondary Education ◽  
Life Transition ◽  
Full Time ◽  
Major Life ◽  
Long Term Stability ◽  
Time Period ◽  
Transition From High School

Abstract. The concept of emotional intelligence (EI) has attracted growing interest from researchers working in various fields. The present study examined the long-term stability (32 months) of EI-related abilities over the course of a major life transition (the transition from high school to university). During the first week of full-time study, a large group of undergraduates completed the EQ-i:Short; 32 months later a random subset of these students (N = 238), who had started their postsecondary education within 24 months of graduating from high school, completed the measures for a second time. The study found EI scores to be relatively stable over the 32-month time period. EI scores were also found to be significantly higher at Time 2; the overall pattern of change in EI-levels was more than can be attributed to the increased age of the participants.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

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