This work studied the feasibility of using a solid phase microextraction (SPME) fiber for sampling and analysis of gaseous formaldehyde as well as particulate-bound formaldehyde from burning Chinese incense. The SPME fiber with PDMS/DVB coating were partially coated with o-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride (PFBHA), and used for sampling formaldehyde. The sampling rate fo...

Multi-phased designs and biased sampling designs are two of the well recognized approaches to enhance study efficiency. In this paper, we propose a new and cost-effective sampling design, the two-phase probability dependent sampling design (PDS), for studies with a continuous outcome. This design will enable investigators to make efficient use of resources by targeting more informative subjects...

Control systems are mostly modelled in continuous time. Implementation however happens in general by digital computers (mostly microprocessors), which influences the behavior of the control system. This makes a well-defined method for modelling of digital control systems desirable. In the past Mecal Applied Mechanics BV simulated digital control systems as an analog system with a time delay in ...

Non-response or other missingness may be occurred in various forms. In this paper, we consider unit non-response, and hence make attempts for adjustments by appropriate weighting. Our special exercise is concerned a two-phase sampling case so that, first, a large sample survey has been conducted with a rather general questionnaire. In the end of this face-to-face contact the interviewer has ask...