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Celery (Avium graveolens L.) has been naturally used to treat hypertension and cancer. Fresh celery contains a high water content of approximately ±86% which may lower the quality upon storage for a long time. Drying was applied to reduce moisture content in order to prolong the shelf-life. Drying of celery was carried out using a self-designed photovoltaic-thermal (PV/T) solar dryer as well as conventional dryers such as oven and vacuum oven for the comparisons at an approximate temperature of 49°C. The PV/T solar dryer was able to simultaneously convert the solar energy into thermal and electrical energy. The electrical energy was in turn used to drive the blowers to create a forced convective flow of heat transfer. Drying in the PV/T solar dryer was carried out in 3 different weather conditions while 3 different pressures (10; 40; 70 kPa) were tested during drying in the vacuum oven. The PV/T solar dryers demonstrated the best results in terms of constant drying rate (0.986 kg H2O/min.m2) and drying time (87 minutes). Total chlorophyll content retained was 5.42 mg/L. The PV/T solar dryer seemed promising to be further developed for an efficient drying process since it required low energy consumption while using the costless renewable solar energy.

High speed downlink packet access (HSDPA) is an extension of the Universal Mobile Telecommunications System (UMTS) technology of 3GPP Rel-99, with the objective to increase the data rate and reduce the latency in the downlink. The main focus of the work presented is to analyse the effect of congestion at the Iub interface on the HSDPA performance. The data flows should be adequately controlled in order to avoid congestion in the transport network. The 3GPP (3rd Generation Partnership Project) Rel. 5 specifications highlight two congestion detection mechanisms which are based on the frame sequence number (FSN) and the delay reference time (DRT) fields of HSDPA data frame. In addition to these, a third congestion detection mechanism based of Checksum of HSDPA data frame is considered. This paper discusses a congestion control scheme deploying all three congestion detection methods. It is shown, that a congestion control algorithm can effectively work using these congestion detection triggers and can control the offered load to the transport network. The simulation results presented in this paper confirm that the congestion in the transport network can be avoided, and hence the performance of HSDPA network can be significantly improved in all aspects.