Faulty readings

If you have determined that your balance is making inaccurate measurements and you have eliminated human error, you not only cannot trust any future weighings, you must question all past weighings to the point of the last balance verification. By maintaining written records of balance accuracy tests on a routine basis, the reliability of past measurements can be verified. Otherwise, every weighing made between the last verification and the first appearance of faulty readings is in... 

Dr. Crummett concludes his discussion, "The use of inappropriate sampling analytical methodology or faulty technique brings false numbers Into the data set of the laboratory report. These may then be communicated to the public. Misinterpretations and faulty reading of the laboratory report may also cause headlines in newspapers which convey a message contrary to the data in the initial laboratory report. 

Accident Analyses. Among the written documentation used for obtaining ergonomic data are accident statistics and reports. It should be mentioned, however, that the content of such documentation is somewhat unreliable, especially where the description of human error is concerned. Since accidents occur relatively rarely, an alternative approach is to study critical incidents instead of accidents. These are intermediate events which do not result in accidents, e.g., the faulty reading of an airplane instrument. The required information is obtained by means of interviews or questionnaires, whereby it is of vital importance to convince the respondents of the confidentiality of their statements. 

Figure 6.67 Percentage of faulty readings in an experiment comparing scales of different forms (from Grandjean [6-6]).

In the absence of an AGAC the ribosomes will prodnce the artificial polypeptides, polyphenylalanine (as specified by the codon UUU) or polyproline (as specified by the codon CCC). However, when streptomycin is added, the ribosomes prodnce a mixture of polythreonine (codon ACU) and poly serine (codon UCU). The misreading of the codons does not appear to be random U is read as A or C and C is read as A or U. If such misreading occurs in whole cells the accumulation of non-functional or toxic proteins would eventually prove fatal to the cells. There is some evidence that the bacterial cell membrane is damaged when the cells attempt to excrete the faulty proteins. 

Conventional nuclear reactors and advanced breeder reactors were America s primary energy strategy since the 1950s to resolve the fossil fuel problem but when a reactor accident occurred in 1979 at Three Mile Island in Pennsylvania, public and investor confidence in nuclear fission dropped. The accident was triggered by the failure of a feedwater pump that supplied water to the steam generators. The backup feedwater pumps were not connected to the system as required, which caused the reactor to heat up. The safety valve then failed to act which allowed a radioactive water and gas leak. This was the worst nuclear power accident in the U.S., but in this accident no one was killed and no one was directly injured. At Three Mile Island faulty instrumentation gave incorrect readings for the... 

When Bohr published his first paper on the topic in 1921, the physicists who read it were convinced that his results were based on undisclosed calculations. They didn t see how so complex a theory could be worked out without making use of some mathematical foundation. But they were wrong. Bohr often proceeded intuitively, using whatever principle seemed most appropriate, as he considered one or another of the elements. Given his methods, it isn t surprising that Bohr made some faulty assignments. Nevertheless, his picture of atomic structure is basically the same as the one used by chemists and physicists today. 

Another method to process and detect faulty responses of the redundant sensor signal is called the likelihood test. The likelihood test used is borrowed from nuclear reactor safety for pressure sensors deciding shutdown or no shutdown. Instead of shutdown or no shutdown for this case, the sensor reading would be rejected or accepted. For accuracy of the readings, the test chosen needs to reject readings that have even the smallest likelihood of being false and leading to the patient s inappropriate response.36... 

In the event that key temperature sensing instruments become inoperative, there are several alternate methods that may be used. Some applications utilize installed spare temperature detectors or dual-element RTDs. The dual-element RTD has two sensing elements of which only one is normally connected. If the operating element becomes faulty, the second element may be used to provide temperature indication. If an installed spare is not utilized, a contact pyrometer (portable thermocouple) may be used to obtain temperature readings on those pieces of equipment or systems that are accessible. 

Locate the error. Try to determine the error as you read the sentence. What s wrong with the underlined portion Is it a run-on sentence, does it have faulty parallelism, or does it have unnecessary wordiness If you determine there is no error (remember, approximately 20% of the questions will be error-free), select choice a and move on to the next question. 

Examples of systematic error are a calibration error in the instrument, failure to establish properly a zero reading of the instrument scale, improper graduation or ahgmnent of an instrumental scale, uncompensated instrumental drift, leakage of material (e.g., of gas in a pressure or vacuum system) or of electricity (in an electrical circuit), and incomplete fulfillment of necessary experimental conditions (e.g., incomplete reaction in a calorimeter, incomplete dehydration of a sample prior to weighing). An example of another kind is faulty theoretical treatment of the results of the measurements to obtain the desired result, perhaps through a faulty approximation in the phenomenological theory involved. 

A common source of random error is carelessness, e.g. reading a scale in the wrong direction or parallax errors. This can be reduced greatly by careful recording and may be detected by repeating the measurement. Other errors arise from faulty or inaccurate equipment, but even a perfectly functioning machine has distinct limits to the accuracy and precision of its measurements. These limits are often quoted in manufacturers specifications and are applicable when an instrument is new however, you should allow for some deterioration with age. 

To standardize the pH meter, select two buffer solutions for standardization whose difference in pH does not exceed 4 units, and such that the expected pH of the material under test falls between them. Fill the cell with one of the buffer solutions for standardization at the temperature at which the test material is to be measured. Set the control "temperature" at the temperature of the solution, and adjust the calibration control to make the observed pH value identical with that tabulated. Rinse the electrodes and the cell with several portions of the second buffer solution for standardization, then fill the cell with it, at the same temperature as the material to be measured. The pH of the second buffer solution is within +0.07 pH emit of the tabulated value. If a larger deviation is noted, examine the electrodes and, if they are faulty, replace them. Adjust the "slope" or "temperature" control to make the observed pH value identical with that tabulated. Repeat the standardization tmtil both buffer solutions for standardization give observed pH values within 0.02 pH unit of the tabulated value without further adjustment of the control. When the system functions satisfactorily, rinse the electrodes and cell several times with a few portions of the test material, fill the cell with the test material, and read the pH value. Use carbon dioxide-free water for solution or dilution of test material in pH determinations. In all pH measurements, allow a sufficient time for stabilization. 

The worst nuclear power accident in the U.S. occurred at the Three Mile Island plant in Pennsylvania. In this accident no one was killed and no one was directly injured. The event at Three Mile Island occurred from faulty instrumentation that gave erroneous readings for the reactor vessel environment. A series of equipment failures and human errors along with inadequate instrumentation allowed the reactor core to be compromised and go into a partial melt. The radioactive water that was released from the core was confined within the containment building and very little radiation was released. In the Three Mile Island incident, the safety devices worked as planned and prevented any serious injury. This accident resulted in improved procedures, instrumentation, and safety systems being implemented. 

Pressure too low Lower than expected system pressure is caused by leaks (piston seal, column connections, injector), pump malfunctions (lost prime, air bubbles in pump head, vapor lock, faulty check valves,broken piston), or inadequate solvent supply (empty solvent reservoir, plugged solvent sinker, bent solvent lines, or wrong solvent mixture). Problem diagnostics can be made by visual inspection for leaks and by monitoring the pressure reading of the pump. 

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