Mech 226 Exercise 3

A: Construction & Green Roofs 1. One panel of the exterior concrete at the southwest corner of level 01/02 lacks eyebrow protection. As a result, this section will be subject to increased runoff, causing the silicone elastomeric coating to stain heavily.

2. We recommend that Johnson Engineering provide project specific shop drawings that specify the parts installation sequence at the interfaces and penetrations. Additionally, the fastener type, corrosion resistance and spacing for attachment of the base plate should also be specified.

A: Wind Farms 1. A wind farm may be a single machine, or a composition of many machines. It could even possibly consist of hundreds of wind turbines. Regardless of the wind farm’s size and composition, the construction and design methods do not change.

2. People tend to think of a wind farm as a power station, but there are important differences between these two types of power generation. A conventional power station is one large machine and will not generate power until construction is completed. Additionally, it will often need a substantial and complicated civil structure. In designing such a structure, construction risk will be an important part of the project assessment.

3. The construction of a wind farm is more like the purchasing of a fleet of trucks than the construction of a power station. Similar to the modular approach one takes with a fleet of trucks, the purchasing price of turbines and delivery schedule are both set in advance. Due to this approach, wind farms are seldom finished late or over budget.

B: Conductive Concrete 1. Concrete has been used for many years as a composite material due to its excellent mechanical properties. For instance, it provides excellent durability for construction. However, concrete is a poor electrical conductor, especially under dry climatic conditions. If ever a concrete existed with good electrical conductivity and mechanical properties, it would have important applications. For example, it might be used for de-icing roads from snow.

2. The principle behind an electrically conductive concrete is the use of cement to bind together conductive materials. Such materials include carbon fibre, graphite and coke breeze, which is an inexpensive byproduct of steel production. The materials then form a continuous network of conducting pathways in the concrete.

3. This conductive concrete can be fabricated by two methods. The first method of conventional mixing is done by adding conductive particles and fibers to conventional aggregate and cement paste. Conductive concrete produced this way has relatively higher electrical resistivity and compressive strength. The second method of slurry infiltration can increase compressive and flexural strengths. Additionally, lower resistivity can be obtained.

C: SCADA (Supervisory Control and Data Acquisition) 1. There are systems called supervisory control and data acquisition (SCADA) systems. SCADA systems are usually centralized to monitor and control entire sites. They can also be complexes of systems, if the monitoring and control multiple sites is required. An example of an application of SCADA systems is in tar sands processing facilities which are spread across the country. Additionally, they could also control a series of power generation and distribution systems throughout a province.

2. Most control actions are performed automatically by remote terminal units (RTU) or programmable logic controllers (PLC). For example, at a potato chip processing plant, PLCs may control as little as the flow of inputs, or as much as all the processes. Additionally, operator functions are usually limited to basic over-riding or supervisory actions. The SCADA system may allow operators to change the set points for the flow, or the alarm conditions. For example, at the chip processing plant, they may change the alarm condition for an oil temperature.