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Post-Fire Erosion Following the CZU Lightning Complex Fire: Quantifying Hillslope Erosion and Providing Guidance Towards Improving Post-Fire Response
Get PDFThe size and severity of wildfires have increased in California during recent decades. This trend is highlighted through the CZU Lightning Complex fire of August 2020 which burned over 86,000 acres in the Santa Cruz mountains of California. The fire greatly impacted the Little Creek watershed, a roughly 1,300 acre watershed that exists largely within Cal Poly San Luis Obispo’s Swanton Pacific Ranch (SPR). The current trends of California’s increased wildfire regime are expected to continue, raising concerns regarding the direct and secondary effects on forest watersheds and the effectiveness of current post-fire erosion control management. Accelerated rates of erosion following wildfire have been found to occur due to the loss of vegetation cover and changes in soil physical properties. We measured hillslope erosion from ten plots at SPR using a silt fence erosion trap approach to study regional post-fire erosion dynamics in the second winter following the CZU Lightning Complex fire. Slope steepness, percent soil cover, and percent canopy coverage were found to be significant factors driving changes in post-fire hillslope erosion in a multivariate model (R2=0.88). Field-collected data from the erosion plots was used to inform spatial extrapolation of hillslope erosion and sediment delivery rates for the entire Little Creek watershed under different soil cover and precipitation scenarios using the Universal Soil Loss Equation (USLE). A watershed average hillslope erosion rate was found to be 4.23 tons/acre/year during the study period from October 2021-March 2022, a 53-fold increase when compared to pre-fire erosion rates and surpassing the watershed average soil loss tolerance factor. Annual sediment delivery to streams within the Little Creek watershed was quantified at 1.16 tons/acre from contributing hillslopes, a 58-fold increase from pre-fire sediment delivery. Using the information obtained from the results from this study, a review of scientific literature, and interviews with relevant stakeholders, we also identify current issues limiting the effectives of post-fire erosion control and provide recommended policy changes and best management practices to mitigate these problems. The results of this study provide valuable information and context regarding post-fire erosion dynamics in the Santa Cruz region and inform future managing decisions aimed mitigating accelerated rates of erosion following wildfire
Existing Multipurpose Assembly Building
Get PDFThis report contains the compliance and life safety review of a multi-purpose assembly use building located in Denver, Colorado. The analysis contained within analyzes the prescriptive requirements of the structure as it stands today and then later reviews an alternative approach utilizing a performance based analysis. Due to this determination the building is evaluated as is and it is noted there are particular features that as a newly constructed building would require a different compliance approach.
This building was originally constructed in 1965 and has undergone two major additions. The East addition added the entire lower level in 1978 and expanded the Upper Level to include the Youth lounge and Courtyard. The Chapel addition was completed in 1988 and added the Chapel and West classrooms wing of the building. The structure has two distinct stories, with a basement serving the building as a mechanical support space below grade and an assembly seating balcony in the Sanctuary. The existing facility provides a floor area of approximately 48,300 ft2 and the apex of the sloped roof of the Sanctuary measures 45’ above the finished floor of the Upper Level.
The multi-purpose building functions primarily as a place of worship, but host an array of assembly use activities that the facility support the remainder of the time. In addition to the Group A-3 occupancy there are administrative offices (Group B) and an onsite apartment (Group R-3) for a staff member that due to their size, relative to the assembly use, are considered accessory to the Assembly occupancy. No existing separation is provided between the occupancies but there are area separation walls the split the building into compartments, limiting the fire area. Building A and B were separated during the original construction of the building and consistent with a Type III-B construction materials, being noncombustible exterior walls and no restriction on material in the interior. Building C, D, & E were separated as the additions expanded the floor area and are all considered Type V-B construction type as combustible building materials were used throughout. These separations are provided to limit the fire area in order to remain below the threshold needed for an automatic suppression system in line with a passive fire protection safety plan.
A sprinkler system is not provided in the building, but the kitchen is provided with a wet agent hood system. There is a fire alarm system that provides automatic detection throughout the building and upon detection provides occupant notification using horns and strobes distributed throughout the building. Portable fire extinguishers are provided as required and in the coat room just outside Sanctuary there is an automatic external defibrillator (AED).
A prescriptive-based evaluation of the building general met the intent of the adopted model code and locally amended provisions of to the International Building Code. However, the strict application to code requirements would require an extension of the exit discharge for multiple exterior exits to be in strict compliance. In addition the calculated occupant loads would require that the fire alarm incorporate an Emergency Voice Alarm Communication System to assist in the evacuation efforts. While it has been noted that area separation walls have been implemented to compartmentalize the building to avoid an automatic suppression system the lack of maintaining these barriers so that the areas no longer provide the passive protection that was intended will either need to be repaired and reverified otherwise there is an argument to be had that an automatic fire suppression system and upgrade to the building fire safety plan may be warranted.
In the alternative approach the report identifies a performance-based approach to the protection of the occupants within. This is performed by a comparative analysis of the available time that occupant have before moving though the structure or the risk of exposure to the fire event is determined to exceed the level of acceptable hazard. In the three selected fire scenarios one of the evaluated methods did not meet the objectives and goals that were used as a benchmark to evaluate the following building’s performance.
Based on this evaluation additional recommendations in how to protect the building both in the performance of the design fire that failed the objecting and where the prescriptive requirement were determine to deficient have been identified and discussed herein
Impact of Teaching Practices and Communication Climates on Participation in Computer Science Education
Get PDFOne way to understand teaching is to view it as a people process rather than a presentation of knowledge. It follows that the role of an educator often extends beyond the primary subject matter and into the realm of classroom management. With this in mind, our research aimed to capture the various teaching practices, participation patterns, and communication climates that occur in virtual computer science classrooms. We sought to answer the following research questions related to virtual computer science classrooms at our institution: Who participates in virtual computer science classrooms, and is participation proportional to student demographics? Is there any correlation between the use of teaching best practices and student participation? Is there any correlation between communication climate and student participation?
To answer these questions, we designed and conducted a mixed-method content analysis study on 14 instructor-provided synchronous video lectures. We created a rubric composed of teaching best practices and supportive and defensive communication behaviors. The resulting design employed ethnographic content analysis (ECA) and quantitative content analysis (QCA) methodologies to produce contextually relevant knowledge. Correlational analysis was conducted using Kendall\u27s tau-b correlational algorithm. Our findings suggest female participation was not proportional to student demographics, and no significant correlations between teaching practices and participation patterns were found. However, several significant correlations between communication climate and participation patterns were identified. Specifically, increased communication behaviors displaying equality were positively correlated with classroom dialogue count, unique female participants, female participation, and female first responses
Hypoxic Incubation Chamber
Get PDFThis paper describes the design, manufacturing, and testing of a novel controllable hypoxic incubator with fully functional oxygen gas control and temperature control in a humid environment. On the current market, a majority of the few hypoxic incubators use pre-mixed gas that does not offer precise control over gas concentration. The objective for this project was to create a chamber that allows the user to set the O2 concentration to varying set points of % O2 while maintaining the chamber at a constant body temperature, CO2 level, humidity, and sterility. To start the project, multiple concepts were developed for the chamber design and the control system. These concepts were compared against developed engineering specs and were evaluated amongst the team and sponsor. From there a detailed CAD model was developed and utilized to design the structure and was used as a guide for manufacturing. The control system was prototyped on breadboards via Arduino. This breadboard testing served as the map to solder perf boards, which are utilized as the final structure for the control system. Once all parts were sourced, machined, and assembled for the final chamber and the control system, these subassemblies were integrated together with a regulated gas system via various tubing. The integrated final design underwent a variety of testing to validate the incubator design and control system. Testing was performed throughout the course of this project: material testing, gas leak testing, cell test, temperature control test, and gas control system optimization; however, the most important of these tests were those relating to the environmental control of the incubator. These tests confirmed whether the incubator design was functional as a practical incubator. Testing confirmed that O2 and temperature control maintained in spec over a short and long period of time while maintaining a humid environment. CO2 control optimization had more complications than the O2 hypoxia system. During testing CO2 concentration would typically overshoot the set point, likely due to a lack of precise control over the gas flow. CO2 variability was reduced due to optimization in the code, but not fully mitigated. Future iterations of this chamber could improve upon the CO2 control and streamline the user interface
Reciprocal Frames: The Flat Beam Grillage
Get PDFThis report follows the pursuit of attaining information and researching academic resources regarding the elusive reciprocal frame structures throughout history, in particular the flat beam grillage. In the following pages, the reader should expect to learn about reciprocal frames in a historical context throughout the globe, as well as, gain insight on how to potentially analyze these frames when they span two-dimensionally. As seen in Figure 1 (Pugnale 2011) and Figure 2 (Godthelp 2019), reciprocal frame structures consist of multiple groups of three or more members that are mutually supported. Along the perimeter of the structure, the members are supported by walls, columns, or the ground; where members meet to a certain extent from the ends of an adjacent member, they are supported by such subsequent members. In structural engineering, it is an intuitive instinct to attempt to follow the load path of a structure until the load is safely distributed into the ground. Only considering gravity, when looking at a planar reciprocal frame layout, it is difficult to visualize exactly how the loading is being transferred within the structure. Furthermore, how does one go about doing statics on a problem that is undergoing a perpetual cycle of load transfer? Hopefully, with the data that has been gathered within this research paper, a path can begin to be paved in regard to the design and analysis of two-dimensional reciprocal frames
Locking Solar Tracking Bushing
Get PDFThe contents of this final design review (FDR) outline the progress made by a team of four mechanical engineering students at California Polytechnic State University, San Luis Obispo to solve the problem of torsional galloping in solar tracker panels since the preliminary design review. The project proposed by the sponsor, Christian Friedrich, on behalf of ARaymond is a design for a friction based braking system integrated into a redesigned bushing.
The CDR contains details about the system design, the design justification, the manufacturing plan, and design verification plan. In the system design section, the four manufacturing subsystems (bushing mount, actuation, power screw, and braking system) will be analyzed. This analysis will be expanded upon in the manufacturing plan where the current manufacturing plan for the project deliverable will be explained. The CDR will also detail any changes that have been made since the preliminary design review (PDR). Since the PDR, the frictional force that is needed to dampen the system has been adjusted to emulate the system more accurately. The project objectives are to dampen oscillation through frictional means, withstand gravitational and wind static loads of 7.5 metric tons, and endure wearing for 30 years.
The overall structure of the bushing has been altered in a variety of different ways. First, the outer journal has been completely separated into two parts to increase the available contact area for the band brake which permits multiple different band orientations to test. As a result, the inner journal has increased in axial length in accordance with the outer journal separation. The lever arm system has also been altered to allow the power screw to interface with the lever arm system. The lever arm system also straddles the I-beam support for ease of rotation and proper power screw engagement. In order to accommodate the separation between the outer journals, an additional mounting plate has been incorporated to mount both halves of the outer journal. Finally, the power screw has been re-oriented to be perpendicular with the I-beam to increase support and adjustability
The Effects of Cofermentation of Cider and Apple Pomace on Cider Attributes
Get PDFPhenolics are critical to the sensory attributes and health benefits of hard cider due to their contribution to the flavor, mouthfeel, and antioxidant activity. With the increase in demand for cider, the use of dessert apple varieties has become more common leaving ciders lacking in phenolics. However, a promising method to increase their phenolic content is through maceration with apple pomace. This study evaluated the effect maceration with apple pomace during cider fermentation on the extraction of phenolic compounds, as well as its effect on the sensory properties of the final product. For this study, ciders were fermented with 0% (control), 20%, 35%, and 50% of the average pomace created during production of the apple must. After fermentation, the ciders were analyzed for acid content, total phenolic content (TPC), alcohol by volume (ABV), color, volatile profile, and sensory properties. The ciders fermented with apple pomace went through malolactic fermentation. During the maceration phenolics were extracted which resulted in an increase in phenolic content in cider. Compared to the control, the treatment ciders were also seen to have higher ABV and TPC, lower acidity, and a different aromatic profile: decreased acetaldehyde and increased ethyl acetate, isoamyl alcohol, and phenylethyl alcohol. The color measurements suggests that treatment ciders were lighter, with a higher red and yellow color compared to the control cider. The sensory analysis revealed the treatment ciders were perceived as less acidic and astringent, but more bitter than the controls. This study shows the addition of apple pomace in its native state increases total phenolic content and could be favorable to produce well rounded ciders. This study shows maceration is a promising technique for increasing phenolic content in ciders