David Nagel

Prof. David Nagel


Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 August 2007
Verified
Conference Paper
Closed access
CCChih-Chun Chang
Chih-Chun Chang
SMSead Muftic
Sead Muftic
DNDavid Nagel
David Nagel
Both correct transmission using hashing and protection of messages using encryption in sensor nodes require additional energy. This paper describes our measurement results for energy consumption in CrossBow and Ember sensor nodes for the process of exchanging data messages between nodes both in the clear and in a protected form. Full strength algorithms were loaded into and executed in nodes. It was found that the CPU operates for substantially longer times for both hashing and encryption operations compared to the time for handling messages without any security. The longer radio transmission times due to hashing were especially costly. Hence, security algorithms have great impacts on energy consumption in sensor nodes. For the full operational mode, with CPU processing and also radio transmission of messages, our results indicate that the lifetime of a transmitting node in a security regime is only about one-half of the lifetime without security.

20 October 2023 in Clean Technologies
Verified
Journal Article
Open access
PDF file
DBDina Bakranova
Dina Bakranova
DNDavid Nagel
David Nagel
The rise in the Earth’s surface temperature on an annual basis has stimulated scientific and engineering interest in developing and implementing alternative energy sources. Besides cost, the main requirements for alternative energy sources are renewability and environmental friendliness. A prominent representative that allows the production of “green” energy is the conversion of solar photons into a practical energy source. Among the existing approaches in solar energy conversion, the process of photoelectrochemical (PEC) hydrogen extraction from water, which mimics natural photosynthesis, is promising. However, direct decomposition of water by sunlight is practically impossible since water is transparent to light waves longer than 190 nm. Therefore, applying a photoelectrochemical process using semiconductor materials and organic compounds is necessary. Semiconductor materials possessing appropriately positioned valence and conduction bands are vital constituents of photoelectrodes. Certain materials exhibit semiconductor characteristics that facilitate the reduction-oxidation (RedOx) reaction of water (H2O) under specific circumstances. ZnO holds a unique position in the field of photocatalysis due to its outstanding characteristics, including remarkable electron mobility, high thermal conductivity, transparency, and more. This article offers an overview of studies exploring ZnO’s role as a photocatalyst in the generation of hydrogen from water.

1 October 2007
Verified
Conference Paper
Closed access
CCChih-Chun Chang
Chih-Chun Chang
DNDavid Nagel
David Nagel
SMSead Muftic
Sead Muftic
WSN nodes are usually powered by batteries. Energy consumption during node operation determines battery life. Power consumption depends on the different hardware and software components in a WSN node and their various activities. In order to determine the life of the battery, we must measure the energy consumption of a node that is active in a network. That is, we must know the power consumption and time duration for node activities including computations, and RF transmission and reception. In this paper, we introduce an easy and accurate method for dynamic energy measurements without disturbing the node or network. The method consists of an oscilloscope, which can stream digitized voltages into a PC, which calculates the profile of energy consumption. We employed this capability to determine energy consumption for different security algorithms in CrossBow MICA2 nodes.

1 January 2013 in Journal of Condensed Matter Nuclear Science
Verified
Journal Article
Open access
PDF file
DNDavid Nagel
David Nagel
Small craters have been observed frequently in the surfaces of cathodes from electrochemical LENR experiments. They are generally 1–100 μm in size. The craters vary widely in shape and areal distribution. Two methods were used to determine the energies needed to produce such craters. The resulting energies range from nJ to mJ, depending on the crater size. If craters are caused by LENR, then many nearly simultaneous MeV-level energy releases would have to occur in a very small volume. There are numerous open basic questions regarding the formation and characteristics of craters in LENR cathodes. It remains to be seen if craters will be helpful in understanding the origin and nature of LENR. But already, the existence and features of craters seriously challenge theories that seek to understand LENR.

22 February 2021 in Sensors
Verified
Journal Article
Open access
PDF file
FMFaisal Mohd-Yasin
Faisal Mohd-Yasin
DNDavid Nagel
David Nagel
This perspective explores future research approaches on the use of noise characteristics of microelectromechanical systems (MEMS) devices as a diagnostic tool to assess their quality and reliability. Such a technique has been applied to electronic devices. In comparison to these, however, MEMS have much more diverse materials, structures, and transduction mechanisms. Correspondingly, we must deal with various types of noise sources and a means to separate their contributions. In this paper, we first provide an overview of reliability and noise in MEMS and then suggest a framework to link noise data of specific devices to their quality or reliability. After this, we analyze 13 classes of MEMS and recommend four that are most amenable to this approach. Finally, we propose a noise measurement system to separate the contribution of electrical and mechanical noise sources. Through this perspective, our hope is for current and future designers of MEMS to see the potential benefits of noise in their devices.

23 November 2010 in Journal of Photochemistry and Photobiology A: Chemistry
Verified
Journal Article
Closed access
CCChia-Pin Chang
Chia-Pin Chang
DNDavid Nagel
David Nagel
MZMona Zaghloul
Mona Zaghloul