Operating lifetimes

In additions to improvements in Si, a variety of devices based on compound semiconductors can be expected. Blue lasers witli high brightness and long operating lifetimes already exist in tlie laboratory. LEDs are likely to be used for all lighting purjDoses. The bandwidtli of optical communications will continue to increase witli ever faster semiconductor lasers. 

Another possibiUty is the net payout fraction (NPE), defined as the ratio of the NPT to the operating life of the venture. This is the fraction of the expected operating lifetime needed to recover the discounted investment. 

Fig. 5. Effect of lifetime on profitability. Venture F has a shorter operating lifetime than Venture A, but the same investment and IRR (see Table 4) the NPV is the same at the 10% discount rate. The diagram indicates that the profitabiUty of Venture F is higher than that of Venture A at all discount rates the shorter lifetime leads to a higher annual net return rate (NRR). The IRR rate does not indicate this difference in profitabiUty.

Fig. 6. Effect of investment on profitabiUty. Venture G has a larger investment and sales revenue than Venture A (see Table 4). NPV at 10%, operating lifetime, and IRR are the same for both ventures. The diagram indicates that the profitabiUty of Venture G, as indicated by NRR, is smaller than that for...

In determining the protection current required, the surfaces of the objects to be protected in the water and on the seabed, as well as those of foreign constructions that are electrically connected to the object to be protected, should be isolated. The protection current densities derived from experience and measurements for various sea areas are given in Table 16-3. In exceptional cases measurements must be carried out beforehand at the location of the installation. Such investigations, however, provide little information on the long-term development of the protection current. By using a suitable coating [4], the protection current density in the early years of service will be only about 10% of the values in Table 16-3. For a planned operational lifetime of 30 years, about 50% of these values is necessary. 

C, = amnial average air concentration of pollutant i UR, = unit risk value by inhalation for pollutant i L = operational lifetime of a facility, yr usually assumed to be 70 year... 

If one just concentrates on the radioactive material in SNF, the volume is very small, especially compared to waste from other power production practices. However, one can only discuss the separated radioactive material if it has undergone extensive reprocessing. If SNF is to be isolated, as in a place such as Yucca Mountain, with perhaps 70 miles of tunnels, the volume is that of the interior of this minor mountain. Isolation of up to 100,000 metric tons of SNF in Yucca Mountain means that for the United States, approximately all the SNF made to date and that expected in the operating lifetime of all current reactors can be put there. Approximately 2,000 metric tons of SNF are produced each year in the United States. Waste volume and placement depend on the amount of compaction and consolidation at the sites. The plans for the Yucca Mountain present a realistic and understandable picture of the volume of SNF. 

State-of-the-art polymer LEDs now have operating lifetimes and luminous efficiencies suitable for a wide variety of commercial applications. Furthermore, it is clear that the fundamental limits of polymer LED performance have not yet been reached. With improvements in material synthesis, fabrication techniques, and device design, significant increases in LED performance are to be expected. These improvements should lead to the extensive use of polymer LEDs in future display applications. 

Nondestructive testing (NDT) is used to assess a component or structure during its operational lifetime. Radiography, ultrasonics, eddy currents, acoustic emissions, and other methods are used to detect and monitor flaws that develop during operation (Chapter 7). 

More fluorescence features than just the emission intensity can be used to develop luminescent optosensors with enhanced selectivity and longer operational lifetime. The wavelength dependence of the luminescence (emission spectmm) and of the luminophore absorption (excitation spectrum) is a source of specificity. For instance, the excitation-emission matrix has shown to be a powerful tool to analyze complex mixtures of fluorescent species and fiber-optic devices for in-situ measurements (e.g. 

Operating Lifetime 6 years/ 10 000 readings 5 years / 100 000 readings... 

A biosensor for nitrite [24] was recently proposed for monitoring nitrite concentration in activated sludge exposed to oxic/anoxic cycles. The biosensor contains bacteria reducing only N02 into N20, which is subsequently monitored by a built-in electrochemical sensor. Up to 90% of the response is obtained in about 1 min, and the detection limit is around 5 mg L1, a concentration sufficient for treatment process monitoring. Unfortunately, the maximum operational lifetime of the N02 biosensor is 6 weeks and some problems may occur with time. 

The average lifetime-enhancing factor over the nine movies is at least 3.3 times longer than that measured with full screen on at full brightness, e.g., a panel with 10,000 h operation life under maximum brightness has an effective operation lifetime 33,000 h for video... 

As mentioned in this review, AMPLEDs are especially attractive for motion picture applications. The Pay-Per-View effect in OLED displays reduces power consumption and extends operation lifetime. Motion picture applications also minimize image retention and optimize display homogeneity. AMOLED has been widely viewed as a promising display technology in competing with AMLCD and plasma displays. The dream of using organic semiconductor films for optoelectronic device applications has become a reality. 

Several groups have studied naphthalene substituted anthracene derivatives as hosts or emitter materials in blue OLEDs (121, 202-205) (Scheme 3.63). The Kodak group used ADN as a host and TBP as a dopant in ITO/CuPc/NPD/ADN TBP/Alq3/Mg Ag [241]. They achieved a narrow vibronic emission centered at 465 nm with CIE (0.154, 0.232) and a luminescent efficiency as high as 3.5 cd/A. In comparison, the undoped device shows a broad and featureless bluish-green emission centered at 460 nm with CIE (0.197, 0.257) and an EL efficiency below 2.0 cd/A. The operational lifetimes of the doped device and the undoped device were 4000 and 2000 h at an initial luminance of 636 cd/m2 and 384 cd/m2, respectively. 

Very recently, UDC claimed that they have successfully achieved a luminescent efficiency of 22 cd/A for a sky blue PHOLED with CIE (0.16,0.37) with over 15,000 h operating lifetime at 200 cd/m2 [317], The possible chemical structure of this sky blue emitter probably involves replacing the phenyl ring of phenylpyrazolyl with an extended fluorenyl unit, which has effective emission at room temperature, as presented at a recent ACS meeting by Forrest [318]. 

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